abd8610cd5
The performance of the L2ARC can be tweaked by a number of tunables, which
may be necessary for different workloads:
l2arc_write_max max write bytes per interval
l2arc_write_boost extra write bytes during device warmup
l2arc_noprefetch skip caching prefetched buffers
l2arc_headroom number of max device writes to precache
l2arc_feed_secs seconds between L2ARC writing
l2arc_feed_min_ms min feed interval in milliseconds
l2arc_feed_again turbo L2ARC warmup
l2arc_norw no reads during writes
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov>
Closes #316
4824 lines
133 KiB
C
4824 lines
133 KiB
C
/*
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* CDDL HEADER START
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*
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* The contents of this file are subject to the terms of the
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* Common Development and Distribution License (the "License").
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* You may not use this file except in compliance with the License.
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*
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* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
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* or http://www.opensolaris.org/os/licensing.
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* See the License for the specific language governing permissions
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* and limitations under the License.
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*
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* When distributing Covered Code, include this CDDL HEADER in each
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* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
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* If applicable, add the following below this CDDL HEADER, with the
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* fields enclosed by brackets "[]" replaced with your own identifying
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* information: Portions Copyright [yyyy] [name of copyright owner]
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*
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* CDDL HEADER END
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*/
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/*
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* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
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*/
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/*
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* DVA-based Adjustable Replacement Cache
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*
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* While much of the theory of operation used here is
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* based on the self-tuning, low overhead replacement cache
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* presented by Megiddo and Modha at FAST 2003, there are some
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* significant differences:
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*
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* 1. The Megiddo and Modha model assumes any page is evictable.
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* Pages in its cache cannot be "locked" into memory. This makes
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* the eviction algorithm simple: evict the last page in the list.
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* This also make the performance characteristics easy to reason
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* about. Our cache is not so simple. At any given moment, some
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* subset of the blocks in the cache are un-evictable because we
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* have handed out a reference to them. Blocks are only evictable
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* when there are no external references active. This makes
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* eviction far more problematic: we choose to evict the evictable
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* blocks that are the "lowest" in the list.
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*
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* There are times when it is not possible to evict the requested
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* space. In these circumstances we are unable to adjust the cache
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* size. To prevent the cache growing unbounded at these times we
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* implement a "cache throttle" that slows the flow of new data
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* into the cache until we can make space available.
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*
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* 2. The Megiddo and Modha model assumes a fixed cache size.
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* Pages are evicted when the cache is full and there is a cache
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* miss. Our model has a variable sized cache. It grows with
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* high use, but also tries to react to memory pressure from the
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* operating system: decreasing its size when system memory is
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* tight.
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*
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* 3. The Megiddo and Modha model assumes a fixed page size. All
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* elements of the cache are therefor exactly the same size. So
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* when adjusting the cache size following a cache miss, its simply
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* a matter of choosing a single page to evict. In our model, we
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* have variable sized cache blocks (rangeing from 512 bytes to
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* 128K bytes). We therefor choose a set of blocks to evict to make
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* space for a cache miss that approximates as closely as possible
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* the space used by the new block.
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*
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* See also: "ARC: A Self-Tuning, Low Overhead Replacement Cache"
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* by N. Megiddo & D. Modha, FAST 2003
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*/
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/*
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* The locking model:
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*
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* A new reference to a cache buffer can be obtained in two
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* ways: 1) via a hash table lookup using the DVA as a key,
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* or 2) via one of the ARC lists. The arc_read() interface
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* uses method 1, while the internal arc algorithms for
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* adjusting the cache use method 2. We therefor provide two
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* types of locks: 1) the hash table lock array, and 2) the
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* arc list locks.
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*
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* Buffers do not have their own mutexs, rather they rely on the
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* hash table mutexs for the bulk of their protection (i.e. most
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* fields in the arc_buf_hdr_t are protected by these mutexs).
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*
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* buf_hash_find() returns the appropriate mutex (held) when it
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* locates the requested buffer in the hash table. It returns
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* NULL for the mutex if the buffer was not in the table.
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*
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* buf_hash_remove() expects the appropriate hash mutex to be
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* already held before it is invoked.
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*
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* Each arc state also has a mutex which is used to protect the
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* buffer list associated with the state. When attempting to
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* obtain a hash table lock while holding an arc list lock you
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* must use: mutex_tryenter() to avoid deadlock. Also note that
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* the active state mutex must be held before the ghost state mutex.
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*
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* Arc buffers may have an associated eviction callback function.
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* This function will be invoked prior to removing the buffer (e.g.
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* in arc_do_user_evicts()). Note however that the data associated
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* with the buffer may be evicted prior to the callback. The callback
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* must be made with *no locks held* (to prevent deadlock). Additionally,
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* the users of callbacks must ensure that their private data is
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* protected from simultaneous callbacks from arc_buf_evict()
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* and arc_do_user_evicts().
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*
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* Note that the majority of the performance stats are manipulated
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* with atomic operations.
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*
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* The L2ARC uses the l2arc_buflist_mtx global mutex for the following:
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*
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* - L2ARC buflist creation
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* - L2ARC buflist eviction
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* - L2ARC write completion, which walks L2ARC buflists
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* - ARC header destruction, as it removes from L2ARC buflists
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* - ARC header release, as it removes from L2ARC buflists
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*/
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#include <sys/spa.h>
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#include <sys/zio.h>
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#include <sys/zfs_context.h>
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#include <sys/arc.h>
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#include <sys/refcount.h>
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#include <sys/vdev.h>
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#include <sys/vdev_impl.h>
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#ifdef _KERNEL
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#include <sys/vmsystm.h>
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#include <vm/anon.h>
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#include <sys/fs/swapnode.h>
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#include <sys/dnlc.h>
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#endif
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#include <sys/callb.h>
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#include <sys/kstat.h>
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#include <zfs_fletcher.h>
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static kmutex_t arc_reclaim_thr_lock;
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static kcondvar_t arc_reclaim_thr_cv; /* used to signal reclaim thr */
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static uint8_t arc_thread_exit;
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extern int zfs_write_limit_shift;
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extern uint64_t zfs_write_limit_max;
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extern kmutex_t zfs_write_limit_lock;
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#define ARC_REDUCE_DNLC_PERCENT 3
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uint_t arc_reduce_dnlc_percent = ARC_REDUCE_DNLC_PERCENT;
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typedef enum arc_reclaim_strategy {
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ARC_RECLAIM_AGGR, /* Aggressive reclaim strategy */
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ARC_RECLAIM_CONS /* Conservative reclaim strategy */
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} arc_reclaim_strategy_t;
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/* number of seconds before growing cache again */
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static int arc_grow_retry = 60;
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/* shift of arc_c for calculating both min and max arc_p */
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static int arc_p_min_shift = 4;
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/* log2(fraction of arc to reclaim) */
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static int arc_shrink_shift = 5;
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/*
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* minimum lifespan of a prefetch block in clock ticks
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* (initialized in arc_init())
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*/
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static int arc_min_prefetch_lifespan;
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static int arc_dead;
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/*
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* The arc has filled available memory and has now warmed up.
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*/
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static boolean_t arc_warm;
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/*
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* These tunables are for performance analysis.
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*/
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unsigned long zfs_arc_max = 0;
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unsigned long zfs_arc_min = 0;
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unsigned long zfs_arc_meta_limit = 0;
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int zfs_arc_grow_retry = 0;
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int zfs_arc_shrink_shift = 0;
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int zfs_arc_p_min_shift = 0;
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int zfs_arc_reduce_dnlc_percent = 0;
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/*
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* Note that buffers can be in one of 6 states:
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* ARC_anon - anonymous (discussed below)
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* ARC_mru - recently used, currently cached
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* ARC_mru_ghost - recentely used, no longer in cache
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* ARC_mfu - frequently used, currently cached
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* ARC_mfu_ghost - frequently used, no longer in cache
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* ARC_l2c_only - exists in L2ARC but not other states
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* When there are no active references to the buffer, they are
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* are linked onto a list in one of these arc states. These are
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* the only buffers that can be evicted or deleted. Within each
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* state there are multiple lists, one for meta-data and one for
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* non-meta-data. Meta-data (indirect blocks, blocks of dnodes,
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* etc.) is tracked separately so that it can be managed more
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* explicitly: favored over data, limited explicitly.
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*
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* Anonymous buffers are buffers that are not associated with
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* a DVA. These are buffers that hold dirty block copies
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* before they are written to stable storage. By definition,
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* they are "ref'd" and are considered part of arc_mru
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* that cannot be freed. Generally, they will aquire a DVA
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* as they are written and migrate onto the arc_mru list.
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*
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* The ARC_l2c_only state is for buffers that are in the second
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* level ARC but no longer in any of the ARC_m* lists. The second
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* level ARC itself may also contain buffers that are in any of
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* the ARC_m* states - meaning that a buffer can exist in two
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* places. The reason for the ARC_l2c_only state is to keep the
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* buffer header in the hash table, so that reads that hit the
|
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* second level ARC benefit from these fast lookups.
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*/
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typedef struct arc_state {
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list_t arcs_list[ARC_BUFC_NUMTYPES]; /* list of evictable buffers */
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uint64_t arcs_lsize[ARC_BUFC_NUMTYPES]; /* amount of evictable data */
|
|
uint64_t arcs_size; /* total amount of data in this state */
|
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kmutex_t arcs_mtx;
|
|
} arc_state_t;
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|
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/* The 6 states: */
|
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static arc_state_t ARC_anon;
|
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static arc_state_t ARC_mru;
|
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static arc_state_t ARC_mru_ghost;
|
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static arc_state_t ARC_mfu;
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static arc_state_t ARC_mfu_ghost;
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static arc_state_t ARC_l2c_only;
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|
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typedef struct arc_stats {
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kstat_named_t arcstat_hits;
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kstat_named_t arcstat_misses;
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kstat_named_t arcstat_demand_data_hits;
|
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kstat_named_t arcstat_demand_data_misses;
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kstat_named_t arcstat_demand_metadata_hits;
|
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kstat_named_t arcstat_demand_metadata_misses;
|
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kstat_named_t arcstat_prefetch_data_hits;
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kstat_named_t arcstat_prefetch_data_misses;
|
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kstat_named_t arcstat_prefetch_metadata_hits;
|
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kstat_named_t arcstat_prefetch_metadata_misses;
|
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kstat_named_t arcstat_mru_hits;
|
|
kstat_named_t arcstat_mru_ghost_hits;
|
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kstat_named_t arcstat_mfu_hits;
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kstat_named_t arcstat_mfu_ghost_hits;
|
|
kstat_named_t arcstat_deleted;
|
|
kstat_named_t arcstat_recycle_miss;
|
|
kstat_named_t arcstat_mutex_miss;
|
|
kstat_named_t arcstat_evict_skip;
|
|
kstat_named_t arcstat_evict_l2_cached;
|
|
kstat_named_t arcstat_evict_l2_eligible;
|
|
kstat_named_t arcstat_evict_l2_ineligible;
|
|
kstat_named_t arcstat_hash_elements;
|
|
kstat_named_t arcstat_hash_elements_max;
|
|
kstat_named_t arcstat_hash_collisions;
|
|
kstat_named_t arcstat_hash_chains;
|
|
kstat_named_t arcstat_hash_chain_max;
|
|
kstat_named_t arcstat_p;
|
|
kstat_named_t arcstat_c;
|
|
kstat_named_t arcstat_c_min;
|
|
kstat_named_t arcstat_c_max;
|
|
kstat_named_t arcstat_size;
|
|
kstat_named_t arcstat_hdr_size;
|
|
kstat_named_t arcstat_data_size;
|
|
kstat_named_t arcstat_other_size;
|
|
kstat_named_t arcstat_l2_hits;
|
|
kstat_named_t arcstat_l2_misses;
|
|
kstat_named_t arcstat_l2_feeds;
|
|
kstat_named_t arcstat_l2_rw_clash;
|
|
kstat_named_t arcstat_l2_read_bytes;
|
|
kstat_named_t arcstat_l2_write_bytes;
|
|
kstat_named_t arcstat_l2_writes_sent;
|
|
kstat_named_t arcstat_l2_writes_done;
|
|
kstat_named_t arcstat_l2_writes_error;
|
|
kstat_named_t arcstat_l2_writes_hdr_miss;
|
|
kstat_named_t arcstat_l2_evict_lock_retry;
|
|
kstat_named_t arcstat_l2_evict_reading;
|
|
kstat_named_t arcstat_l2_free_on_write;
|
|
kstat_named_t arcstat_l2_abort_lowmem;
|
|
kstat_named_t arcstat_l2_cksum_bad;
|
|
kstat_named_t arcstat_l2_io_error;
|
|
kstat_named_t arcstat_l2_size;
|
|
kstat_named_t arcstat_l2_hdr_size;
|
|
kstat_named_t arcstat_memory_throttle_count;
|
|
kstat_named_t arcstat_memory_direct_count;
|
|
kstat_named_t arcstat_memory_indirect_count;
|
|
kstat_named_t arcstat_no_grow;
|
|
kstat_named_t arcstat_tempreserve;
|
|
kstat_named_t arcstat_loaned_bytes;
|
|
kstat_named_t arcstat_meta_used;
|
|
kstat_named_t arcstat_meta_limit;
|
|
kstat_named_t arcstat_meta_max;
|
|
} arc_stats_t;
|
|
|
|
static arc_stats_t arc_stats = {
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{ "hits", KSTAT_DATA_UINT64 },
|
|
{ "misses", KSTAT_DATA_UINT64 },
|
|
{ "demand_data_hits", KSTAT_DATA_UINT64 },
|
|
{ "demand_data_misses", KSTAT_DATA_UINT64 },
|
|
{ "demand_metadata_hits", KSTAT_DATA_UINT64 },
|
|
{ "demand_metadata_misses", KSTAT_DATA_UINT64 },
|
|
{ "prefetch_data_hits", KSTAT_DATA_UINT64 },
|
|
{ "prefetch_data_misses", KSTAT_DATA_UINT64 },
|
|
{ "prefetch_metadata_hits", KSTAT_DATA_UINT64 },
|
|
{ "prefetch_metadata_misses", KSTAT_DATA_UINT64 },
|
|
{ "mru_hits", KSTAT_DATA_UINT64 },
|
|
{ "mru_ghost_hits", KSTAT_DATA_UINT64 },
|
|
{ "mfu_hits", KSTAT_DATA_UINT64 },
|
|
{ "mfu_ghost_hits", KSTAT_DATA_UINT64 },
|
|
{ "deleted", KSTAT_DATA_UINT64 },
|
|
{ "recycle_miss", KSTAT_DATA_UINT64 },
|
|
{ "mutex_miss", KSTAT_DATA_UINT64 },
|
|
{ "evict_skip", KSTAT_DATA_UINT64 },
|
|
{ "evict_l2_cached", KSTAT_DATA_UINT64 },
|
|
{ "evict_l2_eligible", KSTAT_DATA_UINT64 },
|
|
{ "evict_l2_ineligible", KSTAT_DATA_UINT64 },
|
|
{ "hash_elements", KSTAT_DATA_UINT64 },
|
|
{ "hash_elements_max", KSTAT_DATA_UINT64 },
|
|
{ "hash_collisions", KSTAT_DATA_UINT64 },
|
|
{ "hash_chains", KSTAT_DATA_UINT64 },
|
|
{ "hash_chain_max", KSTAT_DATA_UINT64 },
|
|
{ "p", KSTAT_DATA_UINT64 },
|
|
{ "c", KSTAT_DATA_UINT64 },
|
|
{ "c_min", KSTAT_DATA_UINT64 },
|
|
{ "c_max", KSTAT_DATA_UINT64 },
|
|
{ "size", KSTAT_DATA_UINT64 },
|
|
{ "hdr_size", KSTAT_DATA_UINT64 },
|
|
{ "data_size", KSTAT_DATA_UINT64 },
|
|
{ "other_size", KSTAT_DATA_UINT64 },
|
|
{ "l2_hits", KSTAT_DATA_UINT64 },
|
|
{ "l2_misses", KSTAT_DATA_UINT64 },
|
|
{ "l2_feeds", KSTAT_DATA_UINT64 },
|
|
{ "l2_rw_clash", KSTAT_DATA_UINT64 },
|
|
{ "l2_read_bytes", KSTAT_DATA_UINT64 },
|
|
{ "l2_write_bytes", KSTAT_DATA_UINT64 },
|
|
{ "l2_writes_sent", KSTAT_DATA_UINT64 },
|
|
{ "l2_writes_done", KSTAT_DATA_UINT64 },
|
|
{ "l2_writes_error", KSTAT_DATA_UINT64 },
|
|
{ "l2_writes_hdr_miss", KSTAT_DATA_UINT64 },
|
|
{ "l2_evict_lock_retry", KSTAT_DATA_UINT64 },
|
|
{ "l2_evict_reading", KSTAT_DATA_UINT64 },
|
|
{ "l2_free_on_write", KSTAT_DATA_UINT64 },
|
|
{ "l2_abort_lowmem", KSTAT_DATA_UINT64 },
|
|
{ "l2_cksum_bad", KSTAT_DATA_UINT64 },
|
|
{ "l2_io_error", KSTAT_DATA_UINT64 },
|
|
{ "l2_size", KSTAT_DATA_UINT64 },
|
|
{ "l2_hdr_size", KSTAT_DATA_UINT64 },
|
|
{ "memory_throttle_count", KSTAT_DATA_UINT64 },
|
|
{ "memory_direct_count", KSTAT_DATA_UINT64 },
|
|
{ "memory_indirect_count", KSTAT_DATA_UINT64 },
|
|
{ "arc_no_grow", KSTAT_DATA_UINT64 },
|
|
{ "arc_tempreserve", KSTAT_DATA_UINT64 },
|
|
{ "arc_loaned_bytes", KSTAT_DATA_UINT64 },
|
|
{ "arc_meta_used", KSTAT_DATA_UINT64 },
|
|
{ "arc_meta_limit", KSTAT_DATA_UINT64 },
|
|
{ "arc_meta_max", KSTAT_DATA_UINT64 },
|
|
};
|
|
|
|
#define ARCSTAT(stat) (arc_stats.stat.value.ui64)
|
|
|
|
#define ARCSTAT_INCR(stat, val) \
|
|
atomic_add_64(&arc_stats.stat.value.ui64, (val));
|
|
|
|
#define ARCSTAT_BUMP(stat) ARCSTAT_INCR(stat, 1)
|
|
#define ARCSTAT_BUMPDOWN(stat) ARCSTAT_INCR(stat, -1)
|
|
|
|
#define ARCSTAT_MAX(stat, val) { \
|
|
uint64_t m; \
|
|
while ((val) > (m = arc_stats.stat.value.ui64) && \
|
|
(m != atomic_cas_64(&arc_stats.stat.value.ui64, m, (val)))) \
|
|
continue; \
|
|
}
|
|
|
|
#define ARCSTAT_MAXSTAT(stat) \
|
|
ARCSTAT_MAX(stat##_max, arc_stats.stat.value.ui64)
|
|
|
|
/*
|
|
* We define a macro to allow ARC hits/misses to be easily broken down by
|
|
* two separate conditions, giving a total of four different subtypes for
|
|
* each of hits and misses (so eight statistics total).
|
|
*/
|
|
#define ARCSTAT_CONDSTAT(cond1, stat1, notstat1, cond2, stat2, notstat2, stat) \
|
|
if (cond1) { \
|
|
if (cond2) { \
|
|
ARCSTAT_BUMP(arcstat_##stat1##_##stat2##_##stat); \
|
|
} else { \
|
|
ARCSTAT_BUMP(arcstat_##stat1##_##notstat2##_##stat); \
|
|
} \
|
|
} else { \
|
|
if (cond2) { \
|
|
ARCSTAT_BUMP(arcstat_##notstat1##_##stat2##_##stat); \
|
|
} else { \
|
|
ARCSTAT_BUMP(arcstat_##notstat1##_##notstat2##_##stat);\
|
|
} \
|
|
}
|
|
|
|
kstat_t *arc_ksp;
|
|
static arc_state_t *arc_anon;
|
|
static arc_state_t *arc_mru;
|
|
static arc_state_t *arc_mru_ghost;
|
|
static arc_state_t *arc_mfu;
|
|
static arc_state_t *arc_mfu_ghost;
|
|
static arc_state_t *arc_l2c_only;
|
|
|
|
/*
|
|
* There are several ARC variables that are critical to export as kstats --
|
|
* but we don't want to have to grovel around in the kstat whenever we wish to
|
|
* manipulate them. For these variables, we therefore define them to be in
|
|
* terms of the statistic variable. This assures that we are not introducing
|
|
* the possibility of inconsistency by having shadow copies of the variables,
|
|
* while still allowing the code to be readable.
|
|
*/
|
|
#define arc_size ARCSTAT(arcstat_size) /* actual total arc size */
|
|
#define arc_p ARCSTAT(arcstat_p) /* target size of MRU */
|
|
#define arc_c ARCSTAT(arcstat_c) /* target size of cache */
|
|
#define arc_c_min ARCSTAT(arcstat_c_min) /* min target cache size */
|
|
#define arc_c_max ARCSTAT(arcstat_c_max) /* max target cache size */
|
|
#define arc_no_grow ARCSTAT(arcstat_no_grow)
|
|
#define arc_tempreserve ARCSTAT(arcstat_tempreserve)
|
|
#define arc_loaned_bytes ARCSTAT(arcstat_loaned_bytes)
|
|
#define arc_meta_used ARCSTAT(arcstat_meta_used)
|
|
#define arc_meta_limit ARCSTAT(arcstat_meta_limit)
|
|
#define arc_meta_max ARCSTAT(arcstat_meta_max)
|
|
|
|
typedef struct l2arc_buf_hdr l2arc_buf_hdr_t;
|
|
|
|
typedef struct arc_callback arc_callback_t;
|
|
|
|
struct arc_callback {
|
|
void *acb_private;
|
|
arc_done_func_t *acb_done;
|
|
arc_buf_t *acb_buf;
|
|
zio_t *acb_zio_dummy;
|
|
arc_callback_t *acb_next;
|
|
};
|
|
|
|
typedef struct arc_write_callback arc_write_callback_t;
|
|
|
|
struct arc_write_callback {
|
|
void *awcb_private;
|
|
arc_done_func_t *awcb_ready;
|
|
arc_done_func_t *awcb_done;
|
|
arc_buf_t *awcb_buf;
|
|
};
|
|
|
|
struct arc_buf_hdr {
|
|
/* protected by hash lock */
|
|
dva_t b_dva;
|
|
uint64_t b_birth;
|
|
uint64_t b_cksum0;
|
|
|
|
kmutex_t b_freeze_lock;
|
|
zio_cksum_t *b_freeze_cksum;
|
|
void *b_thawed;
|
|
|
|
arc_buf_hdr_t *b_hash_next;
|
|
arc_buf_t *b_buf;
|
|
uint32_t b_flags;
|
|
uint32_t b_datacnt;
|
|
|
|
arc_callback_t *b_acb;
|
|
kcondvar_t b_cv;
|
|
|
|
/* immutable */
|
|
arc_buf_contents_t b_type;
|
|
uint64_t b_size;
|
|
uint64_t b_spa;
|
|
|
|
/* protected by arc state mutex */
|
|
arc_state_t *b_state;
|
|
list_node_t b_arc_node;
|
|
|
|
/* updated atomically */
|
|
clock_t b_arc_access;
|
|
|
|
/* self protecting */
|
|
refcount_t b_refcnt;
|
|
|
|
l2arc_buf_hdr_t *b_l2hdr;
|
|
list_node_t b_l2node;
|
|
};
|
|
|
|
static arc_buf_t *arc_eviction_list;
|
|
static kmutex_t arc_eviction_mtx;
|
|
static arc_buf_hdr_t arc_eviction_hdr;
|
|
static void arc_get_data_buf(arc_buf_t *buf);
|
|
static void arc_access(arc_buf_hdr_t *buf, kmutex_t *hash_lock);
|
|
static int arc_evict_needed(arc_buf_contents_t type);
|
|
static void arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes);
|
|
|
|
static boolean_t l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *ab);
|
|
|
|
#define GHOST_STATE(state) \
|
|
((state) == arc_mru_ghost || (state) == arc_mfu_ghost || \
|
|
(state) == arc_l2c_only)
|
|
|
|
/*
|
|
* Private ARC flags. These flags are private ARC only flags that will show up
|
|
* in b_flags in the arc_hdr_buf_t. Some flags are publicly declared, and can
|
|
* be passed in as arc_flags in things like arc_read. However, these flags
|
|
* should never be passed and should only be set by ARC code. When adding new
|
|
* public flags, make sure not to smash the private ones.
|
|
*/
|
|
|
|
#define ARC_IN_HASH_TABLE (1 << 9) /* this buffer is hashed */
|
|
#define ARC_IO_IN_PROGRESS (1 << 10) /* I/O in progress for buf */
|
|
#define ARC_IO_ERROR (1 << 11) /* I/O failed for buf */
|
|
#define ARC_FREED_IN_READ (1 << 12) /* buf freed while in read */
|
|
#define ARC_BUF_AVAILABLE (1 << 13) /* block not in active use */
|
|
#define ARC_INDIRECT (1 << 14) /* this is an indirect block */
|
|
#define ARC_FREE_IN_PROGRESS (1 << 15) /* hdr about to be freed */
|
|
#define ARC_L2_WRITING (1 << 16) /* L2ARC write in progress */
|
|
#define ARC_L2_EVICTED (1 << 17) /* evicted during I/O */
|
|
#define ARC_L2_WRITE_HEAD (1 << 18) /* head of write list */
|
|
|
|
#define HDR_IN_HASH_TABLE(hdr) ((hdr)->b_flags & ARC_IN_HASH_TABLE)
|
|
#define HDR_IO_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS)
|
|
#define HDR_IO_ERROR(hdr) ((hdr)->b_flags & ARC_IO_ERROR)
|
|
#define HDR_PREFETCH(hdr) ((hdr)->b_flags & ARC_PREFETCH)
|
|
#define HDR_FREED_IN_READ(hdr) ((hdr)->b_flags & ARC_FREED_IN_READ)
|
|
#define HDR_BUF_AVAILABLE(hdr) ((hdr)->b_flags & ARC_BUF_AVAILABLE)
|
|
#define HDR_FREE_IN_PROGRESS(hdr) ((hdr)->b_flags & ARC_FREE_IN_PROGRESS)
|
|
#define HDR_L2CACHE(hdr) ((hdr)->b_flags & ARC_L2CACHE)
|
|
#define HDR_L2_READING(hdr) ((hdr)->b_flags & ARC_IO_IN_PROGRESS && \
|
|
(hdr)->b_l2hdr != NULL)
|
|
#define HDR_L2_WRITING(hdr) ((hdr)->b_flags & ARC_L2_WRITING)
|
|
#define HDR_L2_EVICTED(hdr) ((hdr)->b_flags & ARC_L2_EVICTED)
|
|
#define HDR_L2_WRITE_HEAD(hdr) ((hdr)->b_flags & ARC_L2_WRITE_HEAD)
|
|
|
|
/*
|
|
* Other sizes
|
|
*/
|
|
|
|
#define HDR_SIZE ((int64_t)sizeof (arc_buf_hdr_t))
|
|
#define L2HDR_SIZE ((int64_t)sizeof (l2arc_buf_hdr_t))
|
|
|
|
/*
|
|
* Hash table routines
|
|
*/
|
|
|
|
#define HT_LOCK_ALIGN 64
|
|
#define HT_LOCK_PAD (P2NPHASE(sizeof (kmutex_t), (HT_LOCK_ALIGN)))
|
|
|
|
struct ht_lock {
|
|
kmutex_t ht_lock;
|
|
#ifdef _KERNEL
|
|
unsigned char pad[HT_LOCK_PAD];
|
|
#endif
|
|
};
|
|
|
|
#define BUF_LOCKS 256
|
|
typedef struct buf_hash_table {
|
|
uint64_t ht_mask;
|
|
arc_buf_hdr_t **ht_table;
|
|
struct ht_lock ht_locks[BUF_LOCKS];
|
|
} buf_hash_table_t;
|
|
|
|
static buf_hash_table_t buf_hash_table;
|
|
|
|
#define BUF_HASH_INDEX(spa, dva, birth) \
|
|
(buf_hash(spa, dva, birth) & buf_hash_table.ht_mask)
|
|
#define BUF_HASH_LOCK_NTRY(idx) (buf_hash_table.ht_locks[idx & (BUF_LOCKS-1)])
|
|
#define BUF_HASH_LOCK(idx) (&(BUF_HASH_LOCK_NTRY(idx).ht_lock))
|
|
#define HDR_LOCK(hdr) \
|
|
(BUF_HASH_LOCK(BUF_HASH_INDEX(hdr->b_spa, &hdr->b_dva, hdr->b_birth)))
|
|
|
|
uint64_t zfs_crc64_table[256];
|
|
|
|
/*
|
|
* Level 2 ARC
|
|
*/
|
|
|
|
#define L2ARC_WRITE_SIZE (8 * 1024 * 1024) /* initial write max */
|
|
#define L2ARC_HEADROOM 2 /* num of writes */
|
|
#define L2ARC_FEED_SECS 1 /* caching interval secs */
|
|
#define L2ARC_FEED_MIN_MS 200 /* min caching interval ms */
|
|
|
|
#define l2arc_writes_sent ARCSTAT(arcstat_l2_writes_sent)
|
|
#define l2arc_writes_done ARCSTAT(arcstat_l2_writes_done)
|
|
|
|
/*
|
|
* L2ARC Performance Tunables
|
|
*/
|
|
unsigned long l2arc_write_max = L2ARC_WRITE_SIZE; /* def max write size */
|
|
unsigned long l2arc_write_boost = L2ARC_WRITE_SIZE; /* extra warmup write */
|
|
unsigned long l2arc_headroom = L2ARC_HEADROOM; /* # of dev writes */
|
|
unsigned long l2arc_feed_secs = L2ARC_FEED_SECS; /* interval seconds */
|
|
unsigned long l2arc_feed_min_ms = L2ARC_FEED_MIN_MS; /* min interval msecs */
|
|
int l2arc_noprefetch = B_TRUE; /* don't cache prefetch bufs */
|
|
int l2arc_feed_again = B_TRUE; /* turbo warmup */
|
|
int l2arc_norw = B_TRUE; /* no reads during writes */
|
|
|
|
/*
|
|
* L2ARC Internals
|
|
*/
|
|
typedef struct l2arc_dev {
|
|
vdev_t *l2ad_vdev; /* vdev */
|
|
spa_t *l2ad_spa; /* spa */
|
|
uint64_t l2ad_hand; /* next write location */
|
|
uint64_t l2ad_write; /* desired write size, bytes */
|
|
uint64_t l2ad_boost; /* warmup write boost, bytes */
|
|
uint64_t l2ad_start; /* first addr on device */
|
|
uint64_t l2ad_end; /* last addr on device */
|
|
uint64_t l2ad_evict; /* last addr eviction reached */
|
|
boolean_t l2ad_first; /* first sweep through */
|
|
boolean_t l2ad_writing; /* currently writing */
|
|
list_t *l2ad_buflist; /* buffer list */
|
|
list_node_t l2ad_node; /* device list node */
|
|
} l2arc_dev_t;
|
|
|
|
static list_t L2ARC_dev_list; /* device list */
|
|
static list_t *l2arc_dev_list; /* device list pointer */
|
|
static kmutex_t l2arc_dev_mtx; /* device list mutex */
|
|
static l2arc_dev_t *l2arc_dev_last; /* last device used */
|
|
static kmutex_t l2arc_buflist_mtx; /* mutex for all buflists */
|
|
static list_t L2ARC_free_on_write; /* free after write buf list */
|
|
static list_t *l2arc_free_on_write; /* free after write list ptr */
|
|
static kmutex_t l2arc_free_on_write_mtx; /* mutex for list */
|
|
static uint64_t l2arc_ndev; /* number of devices */
|
|
|
|
typedef struct l2arc_read_callback {
|
|
arc_buf_t *l2rcb_buf; /* read buffer */
|
|
spa_t *l2rcb_spa; /* spa */
|
|
blkptr_t l2rcb_bp; /* original blkptr */
|
|
zbookmark_t l2rcb_zb; /* original bookmark */
|
|
int l2rcb_flags; /* original flags */
|
|
} l2arc_read_callback_t;
|
|
|
|
typedef struct l2arc_write_callback {
|
|
l2arc_dev_t *l2wcb_dev; /* device info */
|
|
arc_buf_hdr_t *l2wcb_head; /* head of write buflist */
|
|
} l2arc_write_callback_t;
|
|
|
|
struct l2arc_buf_hdr {
|
|
/* protected by arc_buf_hdr mutex */
|
|
l2arc_dev_t *b_dev; /* L2ARC device */
|
|
uint64_t b_daddr; /* disk address, offset byte */
|
|
};
|
|
|
|
typedef struct l2arc_data_free {
|
|
/* protected by l2arc_free_on_write_mtx */
|
|
void *l2df_data;
|
|
size_t l2df_size;
|
|
void (*l2df_func)(void *, size_t);
|
|
list_node_t l2df_list_node;
|
|
} l2arc_data_free_t;
|
|
|
|
static kmutex_t l2arc_feed_thr_lock;
|
|
static kcondvar_t l2arc_feed_thr_cv;
|
|
static uint8_t l2arc_thread_exit;
|
|
|
|
static void l2arc_read_done(zio_t *zio);
|
|
static void l2arc_hdr_stat_add(void);
|
|
static void l2arc_hdr_stat_remove(void);
|
|
|
|
static uint64_t
|
|
buf_hash(uint64_t spa, const dva_t *dva, uint64_t birth)
|
|
{
|
|
uint8_t *vdva = (uint8_t *)dva;
|
|
uint64_t crc = -1ULL;
|
|
int i;
|
|
|
|
ASSERT(zfs_crc64_table[128] == ZFS_CRC64_POLY);
|
|
|
|
for (i = 0; i < sizeof (dva_t); i++)
|
|
crc = (crc >> 8) ^ zfs_crc64_table[(crc ^ vdva[i]) & 0xFF];
|
|
|
|
crc ^= (spa>>8) ^ birth;
|
|
|
|
return (crc);
|
|
}
|
|
|
|
#define BUF_EMPTY(buf) \
|
|
((buf)->b_dva.dva_word[0] == 0 && \
|
|
(buf)->b_dva.dva_word[1] == 0 && \
|
|
(buf)->b_birth == 0)
|
|
|
|
#define BUF_EQUAL(spa, dva, birth, buf) \
|
|
((buf)->b_dva.dva_word[0] == (dva)->dva_word[0]) && \
|
|
((buf)->b_dva.dva_word[1] == (dva)->dva_word[1]) && \
|
|
((buf)->b_birth == birth) && ((buf)->b_spa == spa)
|
|
|
|
static void
|
|
buf_discard_identity(arc_buf_hdr_t *hdr)
|
|
{
|
|
hdr->b_dva.dva_word[0] = 0;
|
|
hdr->b_dva.dva_word[1] = 0;
|
|
hdr->b_birth = 0;
|
|
hdr->b_cksum0 = 0;
|
|
}
|
|
|
|
static arc_buf_hdr_t *
|
|
buf_hash_find(uint64_t spa, const dva_t *dva, uint64_t birth, kmutex_t **lockp)
|
|
{
|
|
uint64_t idx = BUF_HASH_INDEX(spa, dva, birth);
|
|
kmutex_t *hash_lock = BUF_HASH_LOCK(idx);
|
|
arc_buf_hdr_t *buf;
|
|
|
|
mutex_enter(hash_lock);
|
|
for (buf = buf_hash_table.ht_table[idx]; buf != NULL;
|
|
buf = buf->b_hash_next) {
|
|
if (BUF_EQUAL(spa, dva, birth, buf)) {
|
|
*lockp = hash_lock;
|
|
return (buf);
|
|
}
|
|
}
|
|
mutex_exit(hash_lock);
|
|
*lockp = NULL;
|
|
return (NULL);
|
|
}
|
|
|
|
/*
|
|
* Insert an entry into the hash table. If there is already an element
|
|
* equal to elem in the hash table, then the already existing element
|
|
* will be returned and the new element will not be inserted.
|
|
* Otherwise returns NULL.
|
|
*/
|
|
static arc_buf_hdr_t *
|
|
buf_hash_insert(arc_buf_hdr_t *buf, kmutex_t **lockp)
|
|
{
|
|
uint64_t idx = BUF_HASH_INDEX(buf->b_spa, &buf->b_dva, buf->b_birth);
|
|
kmutex_t *hash_lock = BUF_HASH_LOCK(idx);
|
|
arc_buf_hdr_t *fbuf;
|
|
uint32_t i;
|
|
|
|
ASSERT(!HDR_IN_HASH_TABLE(buf));
|
|
*lockp = hash_lock;
|
|
mutex_enter(hash_lock);
|
|
for (fbuf = buf_hash_table.ht_table[idx], i = 0; fbuf != NULL;
|
|
fbuf = fbuf->b_hash_next, i++) {
|
|
if (BUF_EQUAL(buf->b_spa, &buf->b_dva, buf->b_birth, fbuf))
|
|
return (fbuf);
|
|
}
|
|
|
|
buf->b_hash_next = buf_hash_table.ht_table[idx];
|
|
buf_hash_table.ht_table[idx] = buf;
|
|
buf->b_flags |= ARC_IN_HASH_TABLE;
|
|
|
|
/* collect some hash table performance data */
|
|
if (i > 0) {
|
|
ARCSTAT_BUMP(arcstat_hash_collisions);
|
|
if (i == 1)
|
|
ARCSTAT_BUMP(arcstat_hash_chains);
|
|
|
|
ARCSTAT_MAX(arcstat_hash_chain_max, i);
|
|
}
|
|
|
|
ARCSTAT_BUMP(arcstat_hash_elements);
|
|
ARCSTAT_MAXSTAT(arcstat_hash_elements);
|
|
|
|
return (NULL);
|
|
}
|
|
|
|
static void
|
|
buf_hash_remove(arc_buf_hdr_t *buf)
|
|
{
|
|
arc_buf_hdr_t *fbuf, **bufp;
|
|
uint64_t idx = BUF_HASH_INDEX(buf->b_spa, &buf->b_dva, buf->b_birth);
|
|
|
|
ASSERT(MUTEX_HELD(BUF_HASH_LOCK(idx)));
|
|
ASSERT(HDR_IN_HASH_TABLE(buf));
|
|
|
|
bufp = &buf_hash_table.ht_table[idx];
|
|
while ((fbuf = *bufp) != buf) {
|
|
ASSERT(fbuf != NULL);
|
|
bufp = &fbuf->b_hash_next;
|
|
}
|
|
*bufp = buf->b_hash_next;
|
|
buf->b_hash_next = NULL;
|
|
buf->b_flags &= ~ARC_IN_HASH_TABLE;
|
|
|
|
/* collect some hash table performance data */
|
|
ARCSTAT_BUMPDOWN(arcstat_hash_elements);
|
|
|
|
if (buf_hash_table.ht_table[idx] &&
|
|
buf_hash_table.ht_table[idx]->b_hash_next == NULL)
|
|
ARCSTAT_BUMPDOWN(arcstat_hash_chains);
|
|
}
|
|
|
|
/*
|
|
* Global data structures and functions for the buf kmem cache.
|
|
*/
|
|
static kmem_cache_t *hdr_cache;
|
|
static kmem_cache_t *buf_cache;
|
|
|
|
static void
|
|
buf_fini(void)
|
|
{
|
|
int i;
|
|
|
|
#if defined(_KERNEL) && defined(HAVE_SPL)
|
|
/* Large allocations which do not require contiguous pages
|
|
* should be using vmem_free() in the linux kernel */
|
|
vmem_free(buf_hash_table.ht_table,
|
|
(buf_hash_table.ht_mask + 1) * sizeof (void *));
|
|
#else
|
|
kmem_free(buf_hash_table.ht_table,
|
|
(buf_hash_table.ht_mask + 1) * sizeof (void *));
|
|
#endif
|
|
for (i = 0; i < BUF_LOCKS; i++)
|
|
mutex_destroy(&buf_hash_table.ht_locks[i].ht_lock);
|
|
kmem_cache_destroy(hdr_cache);
|
|
kmem_cache_destroy(buf_cache);
|
|
}
|
|
|
|
/*
|
|
* Constructor callback - called when the cache is empty
|
|
* and a new buf is requested.
|
|
*/
|
|
/* ARGSUSED */
|
|
static int
|
|
hdr_cons(void *vbuf, void *unused, int kmflag)
|
|
{
|
|
arc_buf_hdr_t *buf = vbuf;
|
|
|
|
bzero(buf, sizeof (arc_buf_hdr_t));
|
|
refcount_create(&buf->b_refcnt);
|
|
cv_init(&buf->b_cv, NULL, CV_DEFAULT, NULL);
|
|
mutex_init(&buf->b_freeze_lock, NULL, MUTEX_DEFAULT, NULL);
|
|
list_link_init(&buf->b_arc_node);
|
|
list_link_init(&buf->b_l2node);
|
|
arc_space_consume(sizeof (arc_buf_hdr_t), ARC_SPACE_HDRS);
|
|
|
|
return (0);
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
static int
|
|
buf_cons(void *vbuf, void *unused, int kmflag)
|
|
{
|
|
arc_buf_t *buf = vbuf;
|
|
|
|
bzero(buf, sizeof (arc_buf_t));
|
|
mutex_init(&buf->b_evict_lock, NULL, MUTEX_DEFAULT, NULL);
|
|
rw_init(&buf->b_data_lock, NULL, RW_DEFAULT, NULL);
|
|
arc_space_consume(sizeof (arc_buf_t), ARC_SPACE_HDRS);
|
|
|
|
return (0);
|
|
}
|
|
|
|
/*
|
|
* Destructor callback - called when a cached buf is
|
|
* no longer required.
|
|
*/
|
|
/* ARGSUSED */
|
|
static void
|
|
hdr_dest(void *vbuf, void *unused)
|
|
{
|
|
arc_buf_hdr_t *buf = vbuf;
|
|
|
|
ASSERT(BUF_EMPTY(buf));
|
|
refcount_destroy(&buf->b_refcnt);
|
|
cv_destroy(&buf->b_cv);
|
|
mutex_destroy(&buf->b_freeze_lock);
|
|
arc_space_return(sizeof (arc_buf_hdr_t), ARC_SPACE_HDRS);
|
|
}
|
|
|
|
/* ARGSUSED */
|
|
static void
|
|
buf_dest(void *vbuf, void *unused)
|
|
{
|
|
arc_buf_t *buf = vbuf;
|
|
|
|
mutex_destroy(&buf->b_evict_lock);
|
|
rw_destroy(&buf->b_data_lock);
|
|
arc_space_return(sizeof (arc_buf_t), ARC_SPACE_HDRS);
|
|
}
|
|
|
|
/*
|
|
* Reclaim callback -- invoked when memory is low.
|
|
*/
|
|
/* ARGSUSED */
|
|
static void
|
|
hdr_recl(void *unused)
|
|
{
|
|
dprintf("hdr_recl called\n");
|
|
/*
|
|
* umem calls the reclaim func when we destroy the buf cache,
|
|
* which is after we do arc_fini().
|
|
*/
|
|
if (!arc_dead)
|
|
cv_signal(&arc_reclaim_thr_cv);
|
|
}
|
|
|
|
static void
|
|
buf_init(void)
|
|
{
|
|
uint64_t *ct;
|
|
uint64_t hsize = 1ULL << 12;
|
|
int i, j;
|
|
|
|
/*
|
|
* The hash table is big enough to fill all of physical memory
|
|
* with an average 64K block size. The table will take up
|
|
* totalmem*sizeof(void*)/64K (eg. 128KB/GB with 8-byte pointers).
|
|
*/
|
|
while (hsize * 65536 < physmem * PAGESIZE)
|
|
hsize <<= 1;
|
|
retry:
|
|
buf_hash_table.ht_mask = hsize - 1;
|
|
#if defined(_KERNEL) && defined(HAVE_SPL)
|
|
/* Large allocations which do not require contiguous pages
|
|
* should be using vmem_alloc() in the linux kernel */
|
|
buf_hash_table.ht_table =
|
|
vmem_zalloc(hsize * sizeof (void*), KM_SLEEP);
|
|
#else
|
|
buf_hash_table.ht_table =
|
|
kmem_zalloc(hsize * sizeof (void*), KM_NOSLEEP);
|
|
#endif
|
|
if (buf_hash_table.ht_table == NULL) {
|
|
ASSERT(hsize > (1ULL << 8));
|
|
hsize >>= 1;
|
|
goto retry;
|
|
}
|
|
|
|
hdr_cache = kmem_cache_create("arc_buf_hdr_t", sizeof (arc_buf_hdr_t),
|
|
0, hdr_cons, hdr_dest, hdr_recl, NULL, NULL, 0);
|
|
buf_cache = kmem_cache_create("arc_buf_t", sizeof (arc_buf_t),
|
|
0, buf_cons, buf_dest, NULL, NULL, NULL, 0);
|
|
|
|
for (i = 0; i < 256; i++)
|
|
for (ct = zfs_crc64_table + i, *ct = i, j = 8; j > 0; j--)
|
|
*ct = (*ct >> 1) ^ (-(*ct & 1) & ZFS_CRC64_POLY);
|
|
|
|
for (i = 0; i < BUF_LOCKS; i++) {
|
|
mutex_init(&buf_hash_table.ht_locks[i].ht_lock,
|
|
NULL, MUTEX_DEFAULT, NULL);
|
|
}
|
|
}
|
|
|
|
#define ARC_MINTIME (hz>>4) /* 62 ms */
|
|
|
|
static void
|
|
arc_cksum_verify(arc_buf_t *buf)
|
|
{
|
|
zio_cksum_t zc;
|
|
|
|
if (!(zfs_flags & ZFS_DEBUG_MODIFY))
|
|
return;
|
|
|
|
mutex_enter(&buf->b_hdr->b_freeze_lock);
|
|
if (buf->b_hdr->b_freeze_cksum == NULL ||
|
|
(buf->b_hdr->b_flags & ARC_IO_ERROR)) {
|
|
mutex_exit(&buf->b_hdr->b_freeze_lock);
|
|
return;
|
|
}
|
|
fletcher_2_native(buf->b_data, buf->b_hdr->b_size, &zc);
|
|
if (!ZIO_CHECKSUM_EQUAL(*buf->b_hdr->b_freeze_cksum, zc))
|
|
panic("buffer modified while frozen!");
|
|
mutex_exit(&buf->b_hdr->b_freeze_lock);
|
|
}
|
|
|
|
static int
|
|
arc_cksum_equal(arc_buf_t *buf)
|
|
{
|
|
zio_cksum_t zc;
|
|
int equal;
|
|
|
|
mutex_enter(&buf->b_hdr->b_freeze_lock);
|
|
fletcher_2_native(buf->b_data, buf->b_hdr->b_size, &zc);
|
|
equal = ZIO_CHECKSUM_EQUAL(*buf->b_hdr->b_freeze_cksum, zc);
|
|
mutex_exit(&buf->b_hdr->b_freeze_lock);
|
|
|
|
return (equal);
|
|
}
|
|
|
|
static void
|
|
arc_cksum_compute(arc_buf_t *buf, boolean_t force)
|
|
{
|
|
if (!force && !(zfs_flags & ZFS_DEBUG_MODIFY))
|
|
return;
|
|
|
|
mutex_enter(&buf->b_hdr->b_freeze_lock);
|
|
if (buf->b_hdr->b_freeze_cksum != NULL) {
|
|
mutex_exit(&buf->b_hdr->b_freeze_lock);
|
|
return;
|
|
}
|
|
buf->b_hdr->b_freeze_cksum = kmem_alloc(sizeof (zio_cksum_t), KM_SLEEP);
|
|
fletcher_2_native(buf->b_data, buf->b_hdr->b_size,
|
|
buf->b_hdr->b_freeze_cksum);
|
|
mutex_exit(&buf->b_hdr->b_freeze_lock);
|
|
}
|
|
|
|
void
|
|
arc_buf_thaw(arc_buf_t *buf)
|
|
{
|
|
if (zfs_flags & ZFS_DEBUG_MODIFY) {
|
|
if (buf->b_hdr->b_state != arc_anon)
|
|
panic("modifying non-anon buffer!");
|
|
if (buf->b_hdr->b_flags & ARC_IO_IN_PROGRESS)
|
|
panic("modifying buffer while i/o in progress!");
|
|
arc_cksum_verify(buf);
|
|
}
|
|
|
|
mutex_enter(&buf->b_hdr->b_freeze_lock);
|
|
if (buf->b_hdr->b_freeze_cksum != NULL) {
|
|
kmem_free(buf->b_hdr->b_freeze_cksum, sizeof (zio_cksum_t));
|
|
buf->b_hdr->b_freeze_cksum = NULL;
|
|
}
|
|
|
|
if (zfs_flags & ZFS_DEBUG_MODIFY) {
|
|
if (buf->b_hdr->b_thawed)
|
|
kmem_free(buf->b_hdr->b_thawed, 1);
|
|
buf->b_hdr->b_thawed = kmem_alloc(1, KM_SLEEP);
|
|
}
|
|
|
|
mutex_exit(&buf->b_hdr->b_freeze_lock);
|
|
}
|
|
|
|
void
|
|
arc_buf_freeze(arc_buf_t *buf)
|
|
{
|
|
kmutex_t *hash_lock;
|
|
|
|
if (!(zfs_flags & ZFS_DEBUG_MODIFY))
|
|
return;
|
|
|
|
hash_lock = HDR_LOCK(buf->b_hdr);
|
|
mutex_enter(hash_lock);
|
|
|
|
ASSERT(buf->b_hdr->b_freeze_cksum != NULL ||
|
|
buf->b_hdr->b_state == arc_anon);
|
|
arc_cksum_compute(buf, B_FALSE);
|
|
mutex_exit(hash_lock);
|
|
}
|
|
|
|
static void
|
|
add_reference(arc_buf_hdr_t *ab, kmutex_t *hash_lock, void *tag)
|
|
{
|
|
ASSERT(MUTEX_HELD(hash_lock));
|
|
|
|
if ((refcount_add(&ab->b_refcnt, tag) == 1) &&
|
|
(ab->b_state != arc_anon)) {
|
|
uint64_t delta = ab->b_size * ab->b_datacnt;
|
|
list_t *list = &ab->b_state->arcs_list[ab->b_type];
|
|
uint64_t *size = &ab->b_state->arcs_lsize[ab->b_type];
|
|
|
|
ASSERT(!MUTEX_HELD(&ab->b_state->arcs_mtx));
|
|
mutex_enter(&ab->b_state->arcs_mtx);
|
|
ASSERT(list_link_active(&ab->b_arc_node));
|
|
list_remove(list, ab);
|
|
if (GHOST_STATE(ab->b_state)) {
|
|
ASSERT3U(ab->b_datacnt, ==, 0);
|
|
ASSERT3P(ab->b_buf, ==, NULL);
|
|
delta = ab->b_size;
|
|
}
|
|
ASSERT(delta > 0);
|
|
ASSERT3U(*size, >=, delta);
|
|
atomic_add_64(size, -delta);
|
|
mutex_exit(&ab->b_state->arcs_mtx);
|
|
/* remove the prefetch flag if we get a reference */
|
|
if (ab->b_flags & ARC_PREFETCH)
|
|
ab->b_flags &= ~ARC_PREFETCH;
|
|
}
|
|
}
|
|
|
|
static int
|
|
remove_reference(arc_buf_hdr_t *ab, kmutex_t *hash_lock, void *tag)
|
|
{
|
|
int cnt;
|
|
arc_state_t *state = ab->b_state;
|
|
|
|
ASSERT(state == arc_anon || MUTEX_HELD(hash_lock));
|
|
ASSERT(!GHOST_STATE(state));
|
|
|
|
if (((cnt = refcount_remove(&ab->b_refcnt, tag)) == 0) &&
|
|
(state != arc_anon)) {
|
|
uint64_t *size = &state->arcs_lsize[ab->b_type];
|
|
|
|
ASSERT(!MUTEX_HELD(&state->arcs_mtx));
|
|
mutex_enter(&state->arcs_mtx);
|
|
ASSERT(!list_link_active(&ab->b_arc_node));
|
|
list_insert_head(&state->arcs_list[ab->b_type], ab);
|
|
ASSERT(ab->b_datacnt > 0);
|
|
atomic_add_64(size, ab->b_size * ab->b_datacnt);
|
|
mutex_exit(&state->arcs_mtx);
|
|
}
|
|
return (cnt);
|
|
}
|
|
|
|
/*
|
|
* Move the supplied buffer to the indicated state. The mutex
|
|
* for the buffer must be held by the caller.
|
|
*/
|
|
static void
|
|
arc_change_state(arc_state_t *new_state, arc_buf_hdr_t *ab, kmutex_t *hash_lock)
|
|
{
|
|
arc_state_t *old_state = ab->b_state;
|
|
int64_t refcnt = refcount_count(&ab->b_refcnt);
|
|
uint64_t from_delta, to_delta;
|
|
|
|
ASSERT(MUTEX_HELD(hash_lock));
|
|
ASSERT(new_state != old_state);
|
|
ASSERT(refcnt == 0 || ab->b_datacnt > 0);
|
|
ASSERT(ab->b_datacnt == 0 || !GHOST_STATE(new_state));
|
|
ASSERT(ab->b_datacnt <= 1 || old_state != arc_anon);
|
|
|
|
from_delta = to_delta = ab->b_datacnt * ab->b_size;
|
|
|
|
/*
|
|
* If this buffer is evictable, transfer it from the
|
|
* old state list to the new state list.
|
|
*/
|
|
if (refcnt == 0) {
|
|
if (old_state != arc_anon) {
|
|
int use_mutex = !MUTEX_HELD(&old_state->arcs_mtx);
|
|
uint64_t *size = &old_state->arcs_lsize[ab->b_type];
|
|
|
|
if (use_mutex)
|
|
mutex_enter(&old_state->arcs_mtx);
|
|
|
|
ASSERT(list_link_active(&ab->b_arc_node));
|
|
list_remove(&old_state->arcs_list[ab->b_type], ab);
|
|
|
|
/*
|
|
* If prefetching out of the ghost cache,
|
|
* we will have a non-zero datacnt.
|
|
*/
|
|
if (GHOST_STATE(old_state) && ab->b_datacnt == 0) {
|
|
/* ghost elements have a ghost size */
|
|
ASSERT(ab->b_buf == NULL);
|
|
from_delta = ab->b_size;
|
|
}
|
|
ASSERT3U(*size, >=, from_delta);
|
|
atomic_add_64(size, -from_delta);
|
|
|
|
if (use_mutex)
|
|
mutex_exit(&old_state->arcs_mtx);
|
|
}
|
|
if (new_state != arc_anon) {
|
|
int use_mutex = !MUTEX_HELD(&new_state->arcs_mtx);
|
|
uint64_t *size = &new_state->arcs_lsize[ab->b_type];
|
|
|
|
if (use_mutex)
|
|
mutex_enter(&new_state->arcs_mtx);
|
|
|
|
list_insert_head(&new_state->arcs_list[ab->b_type], ab);
|
|
|
|
/* ghost elements have a ghost size */
|
|
if (GHOST_STATE(new_state)) {
|
|
ASSERT(ab->b_datacnt == 0);
|
|
ASSERT(ab->b_buf == NULL);
|
|
to_delta = ab->b_size;
|
|
}
|
|
atomic_add_64(size, to_delta);
|
|
|
|
if (use_mutex)
|
|
mutex_exit(&new_state->arcs_mtx);
|
|
}
|
|
}
|
|
|
|
ASSERT(!BUF_EMPTY(ab));
|
|
if (new_state == arc_anon && HDR_IN_HASH_TABLE(ab))
|
|
buf_hash_remove(ab);
|
|
|
|
/* adjust state sizes */
|
|
if (to_delta)
|
|
atomic_add_64(&new_state->arcs_size, to_delta);
|
|
if (from_delta) {
|
|
ASSERT3U(old_state->arcs_size, >=, from_delta);
|
|
atomic_add_64(&old_state->arcs_size, -from_delta);
|
|
}
|
|
ab->b_state = new_state;
|
|
|
|
/* adjust l2arc hdr stats */
|
|
if (new_state == arc_l2c_only)
|
|
l2arc_hdr_stat_add();
|
|
else if (old_state == arc_l2c_only)
|
|
l2arc_hdr_stat_remove();
|
|
}
|
|
|
|
void
|
|
arc_space_consume(uint64_t space, arc_space_type_t type)
|
|
{
|
|
ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES);
|
|
|
|
switch (type) {
|
|
default:
|
|
break;
|
|
case ARC_SPACE_DATA:
|
|
ARCSTAT_INCR(arcstat_data_size, space);
|
|
break;
|
|
case ARC_SPACE_OTHER:
|
|
ARCSTAT_INCR(arcstat_other_size, space);
|
|
break;
|
|
case ARC_SPACE_HDRS:
|
|
ARCSTAT_INCR(arcstat_hdr_size, space);
|
|
break;
|
|
case ARC_SPACE_L2HDRS:
|
|
ARCSTAT_INCR(arcstat_l2_hdr_size, space);
|
|
break;
|
|
}
|
|
|
|
atomic_add_64(&arc_meta_used, space);
|
|
atomic_add_64(&arc_size, space);
|
|
}
|
|
|
|
void
|
|
arc_space_return(uint64_t space, arc_space_type_t type)
|
|
{
|
|
ASSERT(type >= 0 && type < ARC_SPACE_NUMTYPES);
|
|
|
|
switch (type) {
|
|
default:
|
|
break;
|
|
case ARC_SPACE_DATA:
|
|
ARCSTAT_INCR(arcstat_data_size, -space);
|
|
break;
|
|
case ARC_SPACE_OTHER:
|
|
ARCSTAT_INCR(arcstat_other_size, -space);
|
|
break;
|
|
case ARC_SPACE_HDRS:
|
|
ARCSTAT_INCR(arcstat_hdr_size, -space);
|
|
break;
|
|
case ARC_SPACE_L2HDRS:
|
|
ARCSTAT_INCR(arcstat_l2_hdr_size, -space);
|
|
break;
|
|
}
|
|
|
|
ASSERT(arc_meta_used >= space);
|
|
if (arc_meta_max < arc_meta_used)
|
|
arc_meta_max = arc_meta_used;
|
|
atomic_add_64(&arc_meta_used, -space);
|
|
ASSERT(arc_size >= space);
|
|
atomic_add_64(&arc_size, -space);
|
|
}
|
|
|
|
void *
|
|
arc_data_buf_alloc(uint64_t size)
|
|
{
|
|
if (arc_evict_needed(ARC_BUFC_DATA))
|
|
cv_signal(&arc_reclaim_thr_cv);
|
|
atomic_add_64(&arc_size, size);
|
|
return (zio_data_buf_alloc(size));
|
|
}
|
|
|
|
void
|
|
arc_data_buf_free(void *buf, uint64_t size)
|
|
{
|
|
zio_data_buf_free(buf, size);
|
|
ASSERT(arc_size >= size);
|
|
atomic_add_64(&arc_size, -size);
|
|
}
|
|
|
|
arc_buf_t *
|
|
arc_buf_alloc(spa_t *spa, int size, void *tag, arc_buf_contents_t type)
|
|
{
|
|
arc_buf_hdr_t *hdr;
|
|
arc_buf_t *buf;
|
|
|
|
ASSERT3U(size, >, 0);
|
|
hdr = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE);
|
|
ASSERT(BUF_EMPTY(hdr));
|
|
hdr->b_size = size;
|
|
hdr->b_type = type;
|
|
hdr->b_spa = spa_guid(spa);
|
|
hdr->b_state = arc_anon;
|
|
hdr->b_arc_access = 0;
|
|
buf = kmem_cache_alloc(buf_cache, KM_PUSHPAGE);
|
|
buf->b_hdr = hdr;
|
|
buf->b_data = NULL;
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
buf->b_next = NULL;
|
|
hdr->b_buf = buf;
|
|
arc_get_data_buf(buf);
|
|
hdr->b_datacnt = 1;
|
|
hdr->b_flags = 0;
|
|
ASSERT(refcount_is_zero(&hdr->b_refcnt));
|
|
(void) refcount_add(&hdr->b_refcnt, tag);
|
|
|
|
return (buf);
|
|
}
|
|
|
|
static char *arc_onloan_tag = "onloan";
|
|
|
|
/*
|
|
* Loan out an anonymous arc buffer. Loaned buffers are not counted as in
|
|
* flight data by arc_tempreserve_space() until they are "returned". Loaned
|
|
* buffers must be returned to the arc before they can be used by the DMU or
|
|
* freed.
|
|
*/
|
|
arc_buf_t *
|
|
arc_loan_buf(spa_t *spa, int size)
|
|
{
|
|
arc_buf_t *buf;
|
|
|
|
buf = arc_buf_alloc(spa, size, arc_onloan_tag, ARC_BUFC_DATA);
|
|
|
|
atomic_add_64(&arc_loaned_bytes, size);
|
|
return (buf);
|
|
}
|
|
|
|
/*
|
|
* Return a loaned arc buffer to the arc.
|
|
*/
|
|
void
|
|
arc_return_buf(arc_buf_t *buf, void *tag)
|
|
{
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
|
|
ASSERT(buf->b_data != NULL);
|
|
(void) refcount_add(&hdr->b_refcnt, tag);
|
|
(void) refcount_remove(&hdr->b_refcnt, arc_onloan_tag);
|
|
|
|
atomic_add_64(&arc_loaned_bytes, -hdr->b_size);
|
|
}
|
|
|
|
/* Detach an arc_buf from a dbuf (tag) */
|
|
void
|
|
arc_loan_inuse_buf(arc_buf_t *buf, void *tag)
|
|
{
|
|
arc_buf_hdr_t *hdr;
|
|
|
|
ASSERT(buf->b_data != NULL);
|
|
hdr = buf->b_hdr;
|
|
(void) refcount_add(&hdr->b_refcnt, arc_onloan_tag);
|
|
(void) refcount_remove(&hdr->b_refcnt, tag);
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
|
|
atomic_add_64(&arc_loaned_bytes, hdr->b_size);
|
|
}
|
|
|
|
static arc_buf_t *
|
|
arc_buf_clone(arc_buf_t *from)
|
|
{
|
|
arc_buf_t *buf;
|
|
arc_buf_hdr_t *hdr = from->b_hdr;
|
|
uint64_t size = hdr->b_size;
|
|
|
|
ASSERT(hdr->b_state != arc_anon);
|
|
|
|
buf = kmem_cache_alloc(buf_cache, KM_PUSHPAGE);
|
|
buf->b_hdr = hdr;
|
|
buf->b_data = NULL;
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
buf->b_next = hdr->b_buf;
|
|
hdr->b_buf = buf;
|
|
arc_get_data_buf(buf);
|
|
bcopy(from->b_data, buf->b_data, size);
|
|
hdr->b_datacnt += 1;
|
|
return (buf);
|
|
}
|
|
|
|
void
|
|
arc_buf_add_ref(arc_buf_t *buf, void* tag)
|
|
{
|
|
arc_buf_hdr_t *hdr;
|
|
kmutex_t *hash_lock;
|
|
|
|
/*
|
|
* Check to see if this buffer is evicted. Callers
|
|
* must verify b_data != NULL to know if the add_ref
|
|
* was successful.
|
|
*/
|
|
mutex_enter(&buf->b_evict_lock);
|
|
if (buf->b_data == NULL) {
|
|
mutex_exit(&buf->b_evict_lock);
|
|
return;
|
|
}
|
|
hash_lock = HDR_LOCK(buf->b_hdr);
|
|
mutex_enter(hash_lock);
|
|
hdr = buf->b_hdr;
|
|
ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
|
|
mutex_exit(&buf->b_evict_lock);
|
|
|
|
ASSERT(hdr->b_state == arc_mru || hdr->b_state == arc_mfu);
|
|
add_reference(hdr, hash_lock, tag);
|
|
DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr);
|
|
arc_access(hdr, hash_lock);
|
|
mutex_exit(hash_lock);
|
|
ARCSTAT_BUMP(arcstat_hits);
|
|
ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH),
|
|
demand, prefetch, hdr->b_type != ARC_BUFC_METADATA,
|
|
data, metadata, hits);
|
|
}
|
|
|
|
/*
|
|
* Free the arc data buffer. If it is an l2arc write in progress,
|
|
* the buffer is placed on l2arc_free_on_write to be freed later.
|
|
*/
|
|
static void
|
|
arc_buf_data_free(arc_buf_hdr_t *hdr, void (*free_func)(void *, size_t),
|
|
void *data, size_t size)
|
|
{
|
|
if (HDR_L2_WRITING(hdr)) {
|
|
l2arc_data_free_t *df;
|
|
df = kmem_alloc(sizeof (l2arc_data_free_t), KM_SLEEP);
|
|
df->l2df_data = data;
|
|
df->l2df_size = size;
|
|
df->l2df_func = free_func;
|
|
mutex_enter(&l2arc_free_on_write_mtx);
|
|
list_insert_head(l2arc_free_on_write, df);
|
|
mutex_exit(&l2arc_free_on_write_mtx);
|
|
ARCSTAT_BUMP(arcstat_l2_free_on_write);
|
|
} else {
|
|
free_func(data, size);
|
|
}
|
|
}
|
|
|
|
static void
|
|
arc_buf_destroy(arc_buf_t *buf, boolean_t recycle, boolean_t all)
|
|
{
|
|
arc_buf_t **bufp;
|
|
|
|
/* free up data associated with the buf */
|
|
if (buf->b_data) {
|
|
arc_state_t *state = buf->b_hdr->b_state;
|
|
uint64_t size = buf->b_hdr->b_size;
|
|
arc_buf_contents_t type = buf->b_hdr->b_type;
|
|
|
|
arc_cksum_verify(buf);
|
|
|
|
if (!recycle) {
|
|
if (type == ARC_BUFC_METADATA) {
|
|
arc_buf_data_free(buf->b_hdr, zio_buf_free,
|
|
buf->b_data, size);
|
|
arc_space_return(size, ARC_SPACE_DATA);
|
|
} else {
|
|
ASSERT(type == ARC_BUFC_DATA);
|
|
arc_buf_data_free(buf->b_hdr,
|
|
zio_data_buf_free, buf->b_data, size);
|
|
ARCSTAT_INCR(arcstat_data_size, -size);
|
|
atomic_add_64(&arc_size, -size);
|
|
}
|
|
}
|
|
if (list_link_active(&buf->b_hdr->b_arc_node)) {
|
|
uint64_t *cnt = &state->arcs_lsize[type];
|
|
|
|
ASSERT(refcount_is_zero(&buf->b_hdr->b_refcnt));
|
|
ASSERT(state != arc_anon);
|
|
|
|
ASSERT3U(*cnt, >=, size);
|
|
atomic_add_64(cnt, -size);
|
|
}
|
|
ASSERT3U(state->arcs_size, >=, size);
|
|
atomic_add_64(&state->arcs_size, -size);
|
|
buf->b_data = NULL;
|
|
ASSERT(buf->b_hdr->b_datacnt > 0);
|
|
buf->b_hdr->b_datacnt -= 1;
|
|
}
|
|
|
|
/* only remove the buf if requested */
|
|
if (!all)
|
|
return;
|
|
|
|
/* remove the buf from the hdr list */
|
|
for (bufp = &buf->b_hdr->b_buf; *bufp != buf; bufp = &(*bufp)->b_next)
|
|
continue;
|
|
*bufp = buf->b_next;
|
|
buf->b_next = NULL;
|
|
|
|
ASSERT(buf->b_efunc == NULL);
|
|
|
|
/* clean up the buf */
|
|
buf->b_hdr = NULL;
|
|
kmem_cache_free(buf_cache, buf);
|
|
}
|
|
|
|
static void
|
|
arc_hdr_destroy(arc_buf_hdr_t *hdr)
|
|
{
|
|
l2arc_buf_hdr_t *l2hdr = hdr->b_l2hdr;
|
|
|
|
ASSERT(refcount_is_zero(&hdr->b_refcnt));
|
|
ASSERT3P(hdr->b_state, ==, arc_anon);
|
|
ASSERT(!HDR_IO_IN_PROGRESS(hdr));
|
|
|
|
if (l2hdr != NULL) {
|
|
boolean_t buflist_held = MUTEX_HELD(&l2arc_buflist_mtx);
|
|
/*
|
|
* To prevent arc_free() and l2arc_evict() from
|
|
* attempting to free the same buffer at the same time,
|
|
* a FREE_IN_PROGRESS flag is given to arc_free() to
|
|
* give it priority. l2arc_evict() can't destroy this
|
|
* header while we are waiting on l2arc_buflist_mtx.
|
|
*
|
|
* The hdr may be removed from l2ad_buflist before we
|
|
* grab l2arc_buflist_mtx, so b_l2hdr is rechecked.
|
|
*/
|
|
if (!buflist_held) {
|
|
mutex_enter(&l2arc_buflist_mtx);
|
|
l2hdr = hdr->b_l2hdr;
|
|
}
|
|
|
|
if (l2hdr != NULL) {
|
|
list_remove(l2hdr->b_dev->l2ad_buflist, hdr);
|
|
ARCSTAT_INCR(arcstat_l2_size, -hdr->b_size);
|
|
kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t));
|
|
if (hdr->b_state == arc_l2c_only)
|
|
l2arc_hdr_stat_remove();
|
|
hdr->b_l2hdr = NULL;
|
|
}
|
|
|
|
if (!buflist_held)
|
|
mutex_exit(&l2arc_buflist_mtx);
|
|
}
|
|
|
|
if (!BUF_EMPTY(hdr)) {
|
|
ASSERT(!HDR_IN_HASH_TABLE(hdr));
|
|
buf_discard_identity(hdr);
|
|
}
|
|
while (hdr->b_buf) {
|
|
arc_buf_t *buf = hdr->b_buf;
|
|
|
|
if (buf->b_efunc) {
|
|
mutex_enter(&arc_eviction_mtx);
|
|
mutex_enter(&buf->b_evict_lock);
|
|
ASSERT(buf->b_hdr != NULL);
|
|
arc_buf_destroy(hdr->b_buf, FALSE, FALSE);
|
|
hdr->b_buf = buf->b_next;
|
|
buf->b_hdr = &arc_eviction_hdr;
|
|
buf->b_next = arc_eviction_list;
|
|
arc_eviction_list = buf;
|
|
mutex_exit(&buf->b_evict_lock);
|
|
mutex_exit(&arc_eviction_mtx);
|
|
} else {
|
|
arc_buf_destroy(hdr->b_buf, FALSE, TRUE);
|
|
}
|
|
}
|
|
if (hdr->b_freeze_cksum != NULL) {
|
|
kmem_free(hdr->b_freeze_cksum, sizeof (zio_cksum_t));
|
|
hdr->b_freeze_cksum = NULL;
|
|
}
|
|
if (hdr->b_thawed) {
|
|
kmem_free(hdr->b_thawed, 1);
|
|
hdr->b_thawed = NULL;
|
|
}
|
|
|
|
ASSERT(!list_link_active(&hdr->b_arc_node));
|
|
ASSERT3P(hdr->b_hash_next, ==, NULL);
|
|
ASSERT3P(hdr->b_acb, ==, NULL);
|
|
kmem_cache_free(hdr_cache, hdr);
|
|
}
|
|
|
|
void
|
|
arc_buf_free(arc_buf_t *buf, void *tag)
|
|
{
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
int hashed = hdr->b_state != arc_anon;
|
|
|
|
ASSERT(buf->b_efunc == NULL);
|
|
ASSERT(buf->b_data != NULL);
|
|
|
|
if (hashed) {
|
|
kmutex_t *hash_lock = HDR_LOCK(hdr);
|
|
|
|
mutex_enter(hash_lock);
|
|
hdr = buf->b_hdr;
|
|
ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
|
|
|
|
(void) remove_reference(hdr, hash_lock, tag);
|
|
if (hdr->b_datacnt > 1) {
|
|
arc_buf_destroy(buf, FALSE, TRUE);
|
|
} else {
|
|
ASSERT(buf == hdr->b_buf);
|
|
ASSERT(buf->b_efunc == NULL);
|
|
hdr->b_flags |= ARC_BUF_AVAILABLE;
|
|
}
|
|
mutex_exit(hash_lock);
|
|
} else if (HDR_IO_IN_PROGRESS(hdr)) {
|
|
int destroy_hdr;
|
|
/*
|
|
* We are in the middle of an async write. Don't destroy
|
|
* this buffer unless the write completes before we finish
|
|
* decrementing the reference count.
|
|
*/
|
|
mutex_enter(&arc_eviction_mtx);
|
|
(void) remove_reference(hdr, NULL, tag);
|
|
ASSERT(refcount_is_zero(&hdr->b_refcnt));
|
|
destroy_hdr = !HDR_IO_IN_PROGRESS(hdr);
|
|
mutex_exit(&arc_eviction_mtx);
|
|
if (destroy_hdr)
|
|
arc_hdr_destroy(hdr);
|
|
} else {
|
|
if (remove_reference(hdr, NULL, tag) > 0)
|
|
arc_buf_destroy(buf, FALSE, TRUE);
|
|
else
|
|
arc_hdr_destroy(hdr);
|
|
}
|
|
}
|
|
|
|
int
|
|
arc_buf_remove_ref(arc_buf_t *buf, void* tag)
|
|
{
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
kmutex_t *hash_lock = HDR_LOCK(hdr);
|
|
int no_callback = (buf->b_efunc == NULL);
|
|
|
|
if (hdr->b_state == arc_anon) {
|
|
ASSERT(hdr->b_datacnt == 1);
|
|
arc_buf_free(buf, tag);
|
|
return (no_callback);
|
|
}
|
|
|
|
mutex_enter(hash_lock);
|
|
hdr = buf->b_hdr;
|
|
ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
|
|
ASSERT(hdr->b_state != arc_anon);
|
|
ASSERT(buf->b_data != NULL);
|
|
|
|
(void) remove_reference(hdr, hash_lock, tag);
|
|
if (hdr->b_datacnt > 1) {
|
|
if (no_callback)
|
|
arc_buf_destroy(buf, FALSE, TRUE);
|
|
} else if (no_callback) {
|
|
ASSERT(hdr->b_buf == buf && buf->b_next == NULL);
|
|
ASSERT(buf->b_efunc == NULL);
|
|
hdr->b_flags |= ARC_BUF_AVAILABLE;
|
|
}
|
|
ASSERT(no_callback || hdr->b_datacnt > 1 ||
|
|
refcount_is_zero(&hdr->b_refcnt));
|
|
mutex_exit(hash_lock);
|
|
return (no_callback);
|
|
}
|
|
|
|
int
|
|
arc_buf_size(arc_buf_t *buf)
|
|
{
|
|
return (buf->b_hdr->b_size);
|
|
}
|
|
|
|
/*
|
|
* Evict buffers from list until we've removed the specified number of
|
|
* bytes. Move the removed buffers to the appropriate evict state.
|
|
* If the recycle flag is set, then attempt to "recycle" a buffer:
|
|
* - look for a buffer to evict that is `bytes' long.
|
|
* - return the data block from this buffer rather than freeing it.
|
|
* This flag is used by callers that are trying to make space for a
|
|
* new buffer in a full arc cache.
|
|
*
|
|
* This function makes a "best effort". It skips over any buffers
|
|
* it can't get a hash_lock on, and so may not catch all candidates.
|
|
* It may also return without evicting as much space as requested.
|
|
*/
|
|
static void *
|
|
arc_evict(arc_state_t *state, uint64_t spa, int64_t bytes, boolean_t recycle,
|
|
arc_buf_contents_t type)
|
|
{
|
|
arc_state_t *evicted_state;
|
|
uint64_t bytes_evicted = 0, skipped = 0, missed = 0;
|
|
arc_buf_hdr_t *ab, *ab_prev = NULL;
|
|
list_t *list = &state->arcs_list[type];
|
|
kmutex_t *hash_lock;
|
|
boolean_t have_lock;
|
|
void *stolen = NULL;
|
|
|
|
ASSERT(state == arc_mru || state == arc_mfu);
|
|
|
|
evicted_state = (state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost;
|
|
|
|
mutex_enter(&state->arcs_mtx);
|
|
mutex_enter(&evicted_state->arcs_mtx);
|
|
|
|
for (ab = list_tail(list); ab; ab = ab_prev) {
|
|
ab_prev = list_prev(list, ab);
|
|
/* prefetch buffers have a minimum lifespan */
|
|
if (HDR_IO_IN_PROGRESS(ab) ||
|
|
(spa && ab->b_spa != spa) ||
|
|
(ab->b_flags & (ARC_PREFETCH|ARC_INDIRECT) &&
|
|
ddi_get_lbolt() - ab->b_arc_access <
|
|
arc_min_prefetch_lifespan)) {
|
|
skipped++;
|
|
continue;
|
|
}
|
|
/* "lookahead" for better eviction candidate */
|
|
if (recycle && ab->b_size != bytes &&
|
|
ab_prev && ab_prev->b_size == bytes)
|
|
continue;
|
|
hash_lock = HDR_LOCK(ab);
|
|
have_lock = MUTEX_HELD(hash_lock);
|
|
if (have_lock || mutex_tryenter(hash_lock)) {
|
|
ASSERT3U(refcount_count(&ab->b_refcnt), ==, 0);
|
|
ASSERT(ab->b_datacnt > 0);
|
|
while (ab->b_buf) {
|
|
arc_buf_t *buf = ab->b_buf;
|
|
if (!mutex_tryenter(&buf->b_evict_lock)) {
|
|
missed += 1;
|
|
break;
|
|
}
|
|
if (buf->b_data) {
|
|
bytes_evicted += ab->b_size;
|
|
if (recycle && ab->b_type == type &&
|
|
ab->b_size == bytes &&
|
|
!HDR_L2_WRITING(ab)) {
|
|
stolen = buf->b_data;
|
|
recycle = FALSE;
|
|
}
|
|
}
|
|
if (buf->b_efunc) {
|
|
mutex_enter(&arc_eviction_mtx);
|
|
arc_buf_destroy(buf,
|
|
buf->b_data == stolen, FALSE);
|
|
ab->b_buf = buf->b_next;
|
|
buf->b_hdr = &arc_eviction_hdr;
|
|
buf->b_next = arc_eviction_list;
|
|
arc_eviction_list = buf;
|
|
mutex_exit(&arc_eviction_mtx);
|
|
mutex_exit(&buf->b_evict_lock);
|
|
} else {
|
|
mutex_exit(&buf->b_evict_lock);
|
|
arc_buf_destroy(buf,
|
|
buf->b_data == stolen, TRUE);
|
|
}
|
|
}
|
|
|
|
if (ab->b_l2hdr) {
|
|
ARCSTAT_INCR(arcstat_evict_l2_cached,
|
|
ab->b_size);
|
|
} else {
|
|
if (l2arc_write_eligible(ab->b_spa, ab)) {
|
|
ARCSTAT_INCR(arcstat_evict_l2_eligible,
|
|
ab->b_size);
|
|
} else {
|
|
ARCSTAT_INCR(
|
|
arcstat_evict_l2_ineligible,
|
|
ab->b_size);
|
|
}
|
|
}
|
|
|
|
if (ab->b_datacnt == 0) {
|
|
arc_change_state(evicted_state, ab, hash_lock);
|
|
ASSERT(HDR_IN_HASH_TABLE(ab));
|
|
ab->b_flags |= ARC_IN_HASH_TABLE;
|
|
ab->b_flags &= ~ARC_BUF_AVAILABLE;
|
|
DTRACE_PROBE1(arc__evict, arc_buf_hdr_t *, ab);
|
|
}
|
|
if (!have_lock)
|
|
mutex_exit(hash_lock);
|
|
if (bytes >= 0 && bytes_evicted >= bytes)
|
|
break;
|
|
} else {
|
|
missed += 1;
|
|
}
|
|
}
|
|
|
|
mutex_exit(&evicted_state->arcs_mtx);
|
|
mutex_exit(&state->arcs_mtx);
|
|
|
|
if (bytes_evicted < bytes)
|
|
dprintf("only evicted %lld bytes from %x\n",
|
|
(longlong_t)bytes_evicted, state);
|
|
|
|
if (skipped)
|
|
ARCSTAT_INCR(arcstat_evict_skip, skipped);
|
|
|
|
if (missed)
|
|
ARCSTAT_INCR(arcstat_mutex_miss, missed);
|
|
|
|
/*
|
|
* We have just evicted some date into the ghost state, make
|
|
* sure we also adjust the ghost state size if necessary.
|
|
*/
|
|
if (arc_no_grow &&
|
|
arc_mru_ghost->arcs_size + arc_mfu_ghost->arcs_size > arc_c) {
|
|
int64_t mru_over = arc_anon->arcs_size + arc_mru->arcs_size +
|
|
arc_mru_ghost->arcs_size - arc_c;
|
|
|
|
if (mru_over > 0 && arc_mru_ghost->arcs_lsize[type] > 0) {
|
|
int64_t todelete =
|
|
MIN(arc_mru_ghost->arcs_lsize[type], mru_over);
|
|
arc_evict_ghost(arc_mru_ghost, 0, todelete);
|
|
} else if (arc_mfu_ghost->arcs_lsize[type] > 0) {
|
|
int64_t todelete = MIN(arc_mfu_ghost->arcs_lsize[type],
|
|
arc_mru_ghost->arcs_size +
|
|
arc_mfu_ghost->arcs_size - arc_c);
|
|
arc_evict_ghost(arc_mfu_ghost, 0, todelete);
|
|
}
|
|
}
|
|
|
|
return (stolen);
|
|
}
|
|
|
|
/*
|
|
* Remove buffers from list until we've removed the specified number of
|
|
* bytes. Destroy the buffers that are removed.
|
|
*/
|
|
static void
|
|
arc_evict_ghost(arc_state_t *state, uint64_t spa, int64_t bytes)
|
|
{
|
|
arc_buf_hdr_t *ab, *ab_prev;
|
|
arc_buf_hdr_t marker;
|
|
list_t *list = &state->arcs_list[ARC_BUFC_DATA];
|
|
kmutex_t *hash_lock;
|
|
uint64_t bytes_deleted = 0;
|
|
uint64_t bufs_skipped = 0;
|
|
|
|
ASSERT(GHOST_STATE(state));
|
|
bzero(&marker, sizeof(marker));
|
|
top:
|
|
mutex_enter(&state->arcs_mtx);
|
|
for (ab = list_tail(list); ab; ab = ab_prev) {
|
|
ab_prev = list_prev(list, ab);
|
|
if (spa && ab->b_spa != spa)
|
|
continue;
|
|
|
|
/* ignore markers */
|
|
if (ab->b_spa == 0)
|
|
continue;
|
|
|
|
hash_lock = HDR_LOCK(ab);
|
|
/* caller may be trying to modify this buffer, skip it */
|
|
if (MUTEX_HELD(hash_lock))
|
|
continue;
|
|
if (mutex_tryenter(hash_lock)) {
|
|
ASSERT(!HDR_IO_IN_PROGRESS(ab));
|
|
ASSERT(ab->b_buf == NULL);
|
|
ARCSTAT_BUMP(arcstat_deleted);
|
|
bytes_deleted += ab->b_size;
|
|
|
|
if (ab->b_l2hdr != NULL) {
|
|
/*
|
|
* This buffer is cached on the 2nd Level ARC;
|
|
* don't destroy the header.
|
|
*/
|
|
arc_change_state(arc_l2c_only, ab, hash_lock);
|
|
mutex_exit(hash_lock);
|
|
} else {
|
|
arc_change_state(arc_anon, ab, hash_lock);
|
|
mutex_exit(hash_lock);
|
|
arc_hdr_destroy(ab);
|
|
}
|
|
|
|
DTRACE_PROBE1(arc__delete, arc_buf_hdr_t *, ab);
|
|
if (bytes >= 0 && bytes_deleted >= bytes)
|
|
break;
|
|
} else if (bytes < 0) {
|
|
/*
|
|
* Insert a list marker and then wait for the
|
|
* hash lock to become available. Once its
|
|
* available, restart from where we left off.
|
|
*/
|
|
list_insert_after(list, ab, &marker);
|
|
mutex_exit(&state->arcs_mtx);
|
|
mutex_enter(hash_lock);
|
|
mutex_exit(hash_lock);
|
|
mutex_enter(&state->arcs_mtx);
|
|
ab_prev = list_prev(list, &marker);
|
|
list_remove(list, &marker);
|
|
} else
|
|
bufs_skipped += 1;
|
|
}
|
|
mutex_exit(&state->arcs_mtx);
|
|
|
|
if (list == &state->arcs_list[ARC_BUFC_DATA] &&
|
|
(bytes < 0 || bytes_deleted < bytes)) {
|
|
list = &state->arcs_list[ARC_BUFC_METADATA];
|
|
goto top;
|
|
}
|
|
|
|
if (bufs_skipped) {
|
|
ARCSTAT_INCR(arcstat_mutex_miss, bufs_skipped);
|
|
ASSERT(bytes >= 0);
|
|
}
|
|
|
|
if (bytes_deleted < bytes)
|
|
dprintf("only deleted %lld bytes from %p\n",
|
|
(longlong_t)bytes_deleted, state);
|
|
}
|
|
|
|
static void
|
|
arc_adjust(void)
|
|
{
|
|
int64_t adjustment, delta;
|
|
|
|
/*
|
|
* Adjust MRU size
|
|
*/
|
|
|
|
adjustment = MIN((int64_t)(arc_size - arc_c),
|
|
(int64_t)(arc_anon->arcs_size + arc_mru->arcs_size + arc_meta_used -
|
|
arc_p));
|
|
|
|
if (adjustment > 0 && arc_mru->arcs_lsize[ARC_BUFC_DATA] > 0) {
|
|
delta = MIN(arc_mru->arcs_lsize[ARC_BUFC_DATA], adjustment);
|
|
(void) arc_evict(arc_mru, 0, delta, FALSE, ARC_BUFC_DATA);
|
|
adjustment -= delta;
|
|
}
|
|
|
|
if (adjustment > 0 && arc_mru->arcs_lsize[ARC_BUFC_METADATA] > 0) {
|
|
delta = MIN(arc_mru->arcs_lsize[ARC_BUFC_METADATA], adjustment);
|
|
(void) arc_evict(arc_mru, 0, delta, FALSE,
|
|
ARC_BUFC_METADATA);
|
|
}
|
|
|
|
/*
|
|
* Adjust MFU size
|
|
*/
|
|
|
|
adjustment = arc_size - arc_c;
|
|
|
|
if (adjustment > 0 && arc_mfu->arcs_lsize[ARC_BUFC_DATA] > 0) {
|
|
delta = MIN(adjustment, arc_mfu->arcs_lsize[ARC_BUFC_DATA]);
|
|
(void) arc_evict(arc_mfu, 0, delta, FALSE, ARC_BUFC_DATA);
|
|
adjustment -= delta;
|
|
}
|
|
|
|
if (adjustment > 0 && arc_mfu->arcs_lsize[ARC_BUFC_METADATA] > 0) {
|
|
int64_t delta = MIN(adjustment,
|
|
arc_mfu->arcs_lsize[ARC_BUFC_METADATA]);
|
|
(void) arc_evict(arc_mfu, 0, delta, FALSE,
|
|
ARC_BUFC_METADATA);
|
|
}
|
|
|
|
/*
|
|
* Adjust ghost lists
|
|
*/
|
|
|
|
adjustment = arc_mru->arcs_size + arc_mru_ghost->arcs_size - arc_c;
|
|
|
|
if (adjustment > 0 && arc_mru_ghost->arcs_size > 0) {
|
|
delta = MIN(arc_mru_ghost->arcs_size, adjustment);
|
|
arc_evict_ghost(arc_mru_ghost, 0, delta);
|
|
}
|
|
|
|
adjustment =
|
|
arc_mru_ghost->arcs_size + arc_mfu_ghost->arcs_size - arc_c;
|
|
|
|
if (adjustment > 0 && arc_mfu_ghost->arcs_size > 0) {
|
|
delta = MIN(arc_mfu_ghost->arcs_size, adjustment);
|
|
arc_evict_ghost(arc_mfu_ghost, 0, delta);
|
|
}
|
|
}
|
|
|
|
static void
|
|
arc_do_user_evicts(void)
|
|
{
|
|
mutex_enter(&arc_eviction_mtx);
|
|
while (arc_eviction_list != NULL) {
|
|
arc_buf_t *buf = arc_eviction_list;
|
|
arc_eviction_list = buf->b_next;
|
|
mutex_enter(&buf->b_evict_lock);
|
|
buf->b_hdr = NULL;
|
|
mutex_exit(&buf->b_evict_lock);
|
|
mutex_exit(&arc_eviction_mtx);
|
|
|
|
if (buf->b_efunc != NULL)
|
|
VERIFY(buf->b_efunc(buf) == 0);
|
|
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
kmem_cache_free(buf_cache, buf);
|
|
mutex_enter(&arc_eviction_mtx);
|
|
}
|
|
mutex_exit(&arc_eviction_mtx);
|
|
}
|
|
|
|
/*
|
|
* Flush all *evictable* data from the cache for the given spa.
|
|
* NOTE: this will not touch "active" (i.e. referenced) data.
|
|
*/
|
|
void
|
|
arc_flush(spa_t *spa)
|
|
{
|
|
uint64_t guid = 0;
|
|
|
|
if (spa)
|
|
guid = spa_guid(spa);
|
|
|
|
while (list_head(&arc_mru->arcs_list[ARC_BUFC_DATA])) {
|
|
(void) arc_evict(arc_mru, guid, -1, FALSE, ARC_BUFC_DATA);
|
|
if (spa)
|
|
break;
|
|
}
|
|
while (list_head(&arc_mru->arcs_list[ARC_BUFC_METADATA])) {
|
|
(void) arc_evict(arc_mru, guid, -1, FALSE, ARC_BUFC_METADATA);
|
|
if (spa)
|
|
break;
|
|
}
|
|
while (list_head(&arc_mfu->arcs_list[ARC_BUFC_DATA])) {
|
|
(void) arc_evict(arc_mfu, guid, -1, FALSE, ARC_BUFC_DATA);
|
|
if (spa)
|
|
break;
|
|
}
|
|
while (list_head(&arc_mfu->arcs_list[ARC_BUFC_METADATA])) {
|
|
(void) arc_evict(arc_mfu, guid, -1, FALSE, ARC_BUFC_METADATA);
|
|
if (spa)
|
|
break;
|
|
}
|
|
|
|
arc_evict_ghost(arc_mru_ghost, guid, -1);
|
|
arc_evict_ghost(arc_mfu_ghost, guid, -1);
|
|
|
|
mutex_enter(&arc_reclaim_thr_lock);
|
|
arc_do_user_evicts();
|
|
mutex_exit(&arc_reclaim_thr_lock);
|
|
ASSERT(spa || arc_eviction_list == NULL);
|
|
}
|
|
|
|
void
|
|
arc_shrink(void)
|
|
{
|
|
if (arc_c > arc_c_min) {
|
|
uint64_t to_free;
|
|
|
|
#ifdef _KERNEL
|
|
to_free = MAX(arc_c >> arc_shrink_shift, ptob(needfree));
|
|
#else
|
|
to_free = arc_c >> arc_shrink_shift;
|
|
#endif
|
|
if (arc_c > arc_c_min + to_free)
|
|
atomic_add_64(&arc_c, -to_free);
|
|
else
|
|
arc_c = arc_c_min;
|
|
|
|
atomic_add_64(&arc_p, -(arc_p >> arc_shrink_shift));
|
|
if (arc_c > arc_size)
|
|
arc_c = MAX(arc_size, arc_c_min);
|
|
if (arc_p > arc_c)
|
|
arc_p = (arc_c >> 1);
|
|
ASSERT(arc_c >= arc_c_min);
|
|
ASSERT((int64_t)arc_p >= 0);
|
|
}
|
|
|
|
if (arc_size > arc_c)
|
|
arc_adjust();
|
|
}
|
|
|
|
static int
|
|
arc_reclaim_needed(void)
|
|
{
|
|
#ifdef _KERNEL
|
|
uint64_t extra;
|
|
|
|
if (needfree)
|
|
return (1);
|
|
|
|
/*
|
|
* take 'desfree' extra pages, so we reclaim sooner, rather than later
|
|
*/
|
|
extra = desfree;
|
|
|
|
/*
|
|
* check that we're out of range of the pageout scanner. It starts to
|
|
* schedule paging if freemem is less than lotsfree and needfree.
|
|
* lotsfree is the high-water mark for pageout, and needfree is the
|
|
* number of needed free pages. We add extra pages here to make sure
|
|
* the scanner doesn't start up while we're freeing memory.
|
|
*/
|
|
if (freemem < lotsfree + needfree + extra)
|
|
return (1);
|
|
|
|
/*
|
|
* check to make sure that swapfs has enough space so that anon
|
|
* reservations can still succeed. anon_resvmem() checks that the
|
|
* availrmem is greater than swapfs_minfree, and the number of reserved
|
|
* swap pages. We also add a bit of extra here just to prevent
|
|
* circumstances from getting really dire.
|
|
*/
|
|
if (availrmem < swapfs_minfree + swapfs_reserve + extra)
|
|
return (1);
|
|
|
|
#if defined(__i386)
|
|
/*
|
|
* If we're on an i386 platform, it's possible that we'll exhaust the
|
|
* kernel heap space before we ever run out of available physical
|
|
* memory. Most checks of the size of the heap_area compare against
|
|
* tune.t_minarmem, which is the minimum available real memory that we
|
|
* can have in the system. However, this is generally fixed at 25 pages
|
|
* which is so low that it's useless. In this comparison, we seek to
|
|
* calculate the total heap-size, and reclaim if more than 3/4ths of the
|
|
* heap is allocated. (Or, in the calculation, if less than 1/4th is
|
|
* free)
|
|
*/
|
|
if (btop(vmem_size(heap_arena, VMEM_FREE)) <
|
|
(btop(vmem_size(heap_arena, VMEM_FREE | VMEM_ALLOC)) >> 2))
|
|
return (1);
|
|
#endif
|
|
|
|
#else
|
|
if (spa_get_random(100) == 0)
|
|
return (1);
|
|
#endif
|
|
return (0);
|
|
}
|
|
|
|
static void
|
|
arc_kmem_reap_now(arc_reclaim_strategy_t strat)
|
|
{
|
|
size_t i;
|
|
kmem_cache_t *prev_cache = NULL;
|
|
kmem_cache_t *prev_data_cache = NULL;
|
|
extern kmem_cache_t *zio_buf_cache[];
|
|
extern kmem_cache_t *zio_data_buf_cache[];
|
|
#ifdef _KERNEL
|
|
int retry = 0;
|
|
|
|
while ((arc_meta_used >= arc_meta_limit) && (retry < 10)) {
|
|
/*
|
|
* We are exceeding our meta-data cache limit.
|
|
* Purge some DNLC entries to release holds on meta-data.
|
|
*/
|
|
dnlc_reduce_cache((void *)(uintptr_t)arc_reduce_dnlc_percent);
|
|
retry++;
|
|
}
|
|
#if defined(__i386)
|
|
/*
|
|
* Reclaim unused memory from all kmem caches.
|
|
*/
|
|
kmem_reap();
|
|
#endif
|
|
#endif
|
|
|
|
/*
|
|
* An aggressive reclamation will shrink the cache size as well as
|
|
* reap free buffers from the arc kmem caches.
|
|
*/
|
|
if (strat == ARC_RECLAIM_AGGR)
|
|
arc_shrink();
|
|
|
|
for (i = 0; i < SPA_MAXBLOCKSIZE >> SPA_MINBLOCKSHIFT; i++) {
|
|
if (zio_buf_cache[i] != prev_cache) {
|
|
prev_cache = zio_buf_cache[i];
|
|
kmem_cache_reap_now(zio_buf_cache[i]);
|
|
}
|
|
if (zio_data_buf_cache[i] != prev_data_cache) {
|
|
prev_data_cache = zio_data_buf_cache[i];
|
|
kmem_cache_reap_now(zio_data_buf_cache[i]);
|
|
}
|
|
}
|
|
kmem_cache_reap_now(buf_cache);
|
|
kmem_cache_reap_now(hdr_cache);
|
|
}
|
|
|
|
static void
|
|
arc_reclaim_thread(void)
|
|
{
|
|
clock_t growtime = 0;
|
|
arc_reclaim_strategy_t last_reclaim = ARC_RECLAIM_CONS;
|
|
callb_cpr_t cpr;
|
|
|
|
CALLB_CPR_INIT(&cpr, &arc_reclaim_thr_lock, callb_generic_cpr, FTAG);
|
|
|
|
mutex_enter(&arc_reclaim_thr_lock);
|
|
while (arc_thread_exit == 0) {
|
|
if (arc_reclaim_needed()) {
|
|
|
|
if (arc_no_grow) {
|
|
if (last_reclaim == ARC_RECLAIM_CONS) {
|
|
last_reclaim = ARC_RECLAIM_AGGR;
|
|
} else {
|
|
last_reclaim = ARC_RECLAIM_CONS;
|
|
}
|
|
} else {
|
|
arc_no_grow = TRUE;
|
|
last_reclaim = ARC_RECLAIM_AGGR;
|
|
membar_producer();
|
|
}
|
|
|
|
/* reset the growth delay for every reclaim */
|
|
growtime = ddi_get_lbolt() + (arc_grow_retry * hz);
|
|
|
|
arc_kmem_reap_now(last_reclaim);
|
|
arc_warm = B_TRUE;
|
|
|
|
} else if (arc_no_grow && ddi_get_lbolt() >= growtime) {
|
|
arc_no_grow = FALSE;
|
|
}
|
|
|
|
/* Keep meta data usage within limits */
|
|
if (arc_meta_used >= arc_meta_limit)
|
|
arc_kmem_reap_now(ARC_RECLAIM_CONS);
|
|
|
|
arc_adjust();
|
|
|
|
if (arc_eviction_list != NULL)
|
|
arc_do_user_evicts();
|
|
|
|
/* block until needed, or one second, whichever is shorter */
|
|
CALLB_CPR_SAFE_BEGIN(&cpr);
|
|
(void) cv_timedwait_interruptible(&arc_reclaim_thr_cv,
|
|
&arc_reclaim_thr_lock, (ddi_get_lbolt() + hz));
|
|
CALLB_CPR_SAFE_END(&cpr, &arc_reclaim_thr_lock);
|
|
}
|
|
|
|
arc_thread_exit = 0;
|
|
cv_broadcast(&arc_reclaim_thr_cv);
|
|
CALLB_CPR_EXIT(&cpr); /* drops arc_reclaim_thr_lock */
|
|
thread_exit();
|
|
}
|
|
|
|
#ifdef _KERNEL
|
|
/*
|
|
* Under Linux the arc shrinker may be called for synchronous (direct)
|
|
* reclaim, or asynchronous (indirect) reclaim. When called by kswapd
|
|
* for indirect reclaim we take a conservative approach and just reap
|
|
* free slabs from the ARC caches. If this proves to be insufficient
|
|
* direct reclaim will be trigger. In direct reclaim a more aggressive
|
|
* strategy is used, data is evicted from the ARC and free slabs reaped.
|
|
*/
|
|
static int
|
|
__arc_shrinker_func(struct shrinker *shrink, struct shrink_control *sc)
|
|
{
|
|
arc_reclaim_strategy_t strategy;
|
|
int arc_reclaim;
|
|
|
|
/* Return number of reclaimable pages based on arc_shrink_shift */
|
|
arc_reclaim = MAX(btop(((int64_t)arc_size - (int64_t)arc_c_min))
|
|
>> arc_shrink_shift, 0);
|
|
if (sc->nr_to_scan == 0)
|
|
return (arc_reclaim);
|
|
|
|
/* Prevent reclaim below arc_c_min */
|
|
if (arc_reclaim <= 0)
|
|
return (-1);
|
|
|
|
/* Not allowed to perform filesystem reclaim */
|
|
if (!(sc->gfp_mask & __GFP_FS))
|
|
return (-1);
|
|
|
|
/* Reclaim in progress */
|
|
if (mutex_tryenter(&arc_reclaim_thr_lock) == 0)
|
|
return (-1);
|
|
|
|
if (current_is_kswapd()) {
|
|
strategy = ARC_RECLAIM_CONS;
|
|
ARCSTAT_INCR(arcstat_memory_indirect_count, 1);
|
|
} else {
|
|
strategy = ARC_RECLAIM_AGGR;
|
|
ARCSTAT_INCR(arcstat_memory_direct_count, 1);
|
|
}
|
|
|
|
arc_kmem_reap_now(strategy);
|
|
arc_reclaim = MAX(btop(((int64_t)arc_size - (int64_t)arc_c_min))
|
|
>> arc_shrink_shift, 0);
|
|
mutex_exit(&arc_reclaim_thr_lock);
|
|
|
|
return (arc_reclaim);
|
|
}
|
|
SPL_SHRINKER_CALLBACK_WRAPPER(arc_shrinker_func);
|
|
|
|
SPL_SHRINKER_DECLARE(arc_shrinker, arc_shrinker_func, DEFAULT_SEEKS);
|
|
#endif /* _KERNEL */
|
|
|
|
/*
|
|
* Adapt arc info given the number of bytes we are trying to add and
|
|
* the state that we are comming from. This function is only called
|
|
* when we are adding new content to the cache.
|
|
*/
|
|
static void
|
|
arc_adapt(int bytes, arc_state_t *state)
|
|
{
|
|
int mult;
|
|
uint64_t arc_p_min = (arc_c >> arc_p_min_shift);
|
|
|
|
if (state == arc_l2c_only)
|
|
return;
|
|
|
|
ASSERT(bytes > 0);
|
|
/*
|
|
* Adapt the target size of the MRU list:
|
|
* - if we just hit in the MRU ghost list, then increase
|
|
* the target size of the MRU list.
|
|
* - if we just hit in the MFU ghost list, then increase
|
|
* the target size of the MFU list by decreasing the
|
|
* target size of the MRU list.
|
|
*/
|
|
if (state == arc_mru_ghost) {
|
|
mult = ((arc_mru_ghost->arcs_size >= arc_mfu_ghost->arcs_size) ?
|
|
1 : (arc_mfu_ghost->arcs_size/arc_mru_ghost->arcs_size));
|
|
mult = MIN(mult, 10); /* avoid wild arc_p adjustment */
|
|
|
|
arc_p = MIN(arc_c - arc_p_min, arc_p + bytes * mult);
|
|
} else if (state == arc_mfu_ghost) {
|
|
uint64_t delta;
|
|
|
|
mult = ((arc_mfu_ghost->arcs_size >= arc_mru_ghost->arcs_size) ?
|
|
1 : (arc_mru_ghost->arcs_size/arc_mfu_ghost->arcs_size));
|
|
mult = MIN(mult, 10);
|
|
|
|
delta = MIN(bytes * mult, arc_p);
|
|
arc_p = MAX(arc_p_min, arc_p - delta);
|
|
}
|
|
ASSERT((int64_t)arc_p >= 0);
|
|
|
|
if (arc_reclaim_needed()) {
|
|
cv_signal(&arc_reclaim_thr_cv);
|
|
return;
|
|
}
|
|
|
|
if (arc_no_grow)
|
|
return;
|
|
|
|
if (arc_c >= arc_c_max)
|
|
return;
|
|
|
|
/*
|
|
* If we're within (2 * maxblocksize) bytes of the target
|
|
* cache size, increment the target cache size
|
|
*/
|
|
if (arc_size > arc_c - (2ULL << SPA_MAXBLOCKSHIFT)) {
|
|
atomic_add_64(&arc_c, (int64_t)bytes);
|
|
if (arc_c > arc_c_max)
|
|
arc_c = arc_c_max;
|
|
else if (state == arc_anon)
|
|
atomic_add_64(&arc_p, (int64_t)bytes);
|
|
if (arc_p > arc_c)
|
|
arc_p = arc_c;
|
|
}
|
|
ASSERT((int64_t)arc_p >= 0);
|
|
}
|
|
|
|
/*
|
|
* Check if the cache has reached its limits and eviction is required
|
|
* prior to insert.
|
|
*/
|
|
static int
|
|
arc_evict_needed(arc_buf_contents_t type)
|
|
{
|
|
if (type == ARC_BUFC_METADATA && arc_meta_used >= arc_meta_limit)
|
|
return (1);
|
|
|
|
#ifdef _KERNEL
|
|
/*
|
|
* If zio data pages are being allocated out of a separate heap segment,
|
|
* then enforce that the size of available vmem for this area remains
|
|
* above about 1/32nd free.
|
|
*/
|
|
if (type == ARC_BUFC_DATA && zio_arena != NULL &&
|
|
vmem_size(zio_arena, VMEM_FREE) <
|
|
(vmem_size(zio_arena, VMEM_ALLOC) >> 5))
|
|
return (1);
|
|
#endif
|
|
|
|
if (arc_reclaim_needed())
|
|
return (1);
|
|
|
|
return (arc_size > arc_c);
|
|
}
|
|
|
|
/*
|
|
* The buffer, supplied as the first argument, needs a data block.
|
|
* So, if we are at cache max, determine which cache should be victimized.
|
|
* We have the following cases:
|
|
*
|
|
* 1. Insert for MRU, p > sizeof(arc_anon + arc_mru) ->
|
|
* In this situation if we're out of space, but the resident size of the MFU is
|
|
* under the limit, victimize the MFU cache to satisfy this insertion request.
|
|
*
|
|
* 2. Insert for MRU, p <= sizeof(arc_anon + arc_mru) ->
|
|
* Here, we've used up all of the available space for the MRU, so we need to
|
|
* evict from our own cache instead. Evict from the set of resident MRU
|
|
* entries.
|
|
*
|
|
* 3. Insert for MFU (c - p) > sizeof(arc_mfu) ->
|
|
* c minus p represents the MFU space in the cache, since p is the size of the
|
|
* cache that is dedicated to the MRU. In this situation there's still space on
|
|
* the MFU side, so the MRU side needs to be victimized.
|
|
*
|
|
* 4. Insert for MFU (c - p) < sizeof(arc_mfu) ->
|
|
* MFU's resident set is consuming more space than it has been allotted. In
|
|
* this situation, we must victimize our own cache, the MFU, for this insertion.
|
|
*/
|
|
static void
|
|
arc_get_data_buf(arc_buf_t *buf)
|
|
{
|
|
arc_state_t *state = buf->b_hdr->b_state;
|
|
uint64_t size = buf->b_hdr->b_size;
|
|
arc_buf_contents_t type = buf->b_hdr->b_type;
|
|
|
|
arc_adapt(size, state);
|
|
|
|
/*
|
|
* We have not yet reached cache maximum size,
|
|
* just allocate a new buffer.
|
|
*/
|
|
if (!arc_evict_needed(type)) {
|
|
if (type == ARC_BUFC_METADATA) {
|
|
buf->b_data = zio_buf_alloc(size);
|
|
arc_space_consume(size, ARC_SPACE_DATA);
|
|
} else {
|
|
ASSERT(type == ARC_BUFC_DATA);
|
|
buf->b_data = zio_data_buf_alloc(size);
|
|
ARCSTAT_INCR(arcstat_data_size, size);
|
|
atomic_add_64(&arc_size, size);
|
|
}
|
|
goto out;
|
|
}
|
|
|
|
/*
|
|
* If we are prefetching from the mfu ghost list, this buffer
|
|
* will end up on the mru list; so steal space from there.
|
|
*/
|
|
if (state == arc_mfu_ghost)
|
|
state = buf->b_hdr->b_flags & ARC_PREFETCH ? arc_mru : arc_mfu;
|
|
else if (state == arc_mru_ghost)
|
|
state = arc_mru;
|
|
|
|
if (state == arc_mru || state == arc_anon) {
|
|
uint64_t mru_used = arc_anon->arcs_size + arc_mru->arcs_size;
|
|
state = (arc_mfu->arcs_lsize[type] >= size &&
|
|
arc_p > mru_used) ? arc_mfu : arc_mru;
|
|
} else {
|
|
/* MFU cases */
|
|
uint64_t mfu_space = arc_c - arc_p;
|
|
state = (arc_mru->arcs_lsize[type] >= size &&
|
|
mfu_space > arc_mfu->arcs_size) ? arc_mru : arc_mfu;
|
|
}
|
|
if ((buf->b_data = arc_evict(state, 0, size, TRUE, type)) == NULL) {
|
|
if (type == ARC_BUFC_METADATA) {
|
|
buf->b_data = zio_buf_alloc(size);
|
|
arc_space_consume(size, ARC_SPACE_DATA);
|
|
} else {
|
|
ASSERT(type == ARC_BUFC_DATA);
|
|
buf->b_data = zio_data_buf_alloc(size);
|
|
ARCSTAT_INCR(arcstat_data_size, size);
|
|
atomic_add_64(&arc_size, size);
|
|
}
|
|
ARCSTAT_BUMP(arcstat_recycle_miss);
|
|
}
|
|
ASSERT(buf->b_data != NULL);
|
|
out:
|
|
/*
|
|
* Update the state size. Note that ghost states have a
|
|
* "ghost size" and so don't need to be updated.
|
|
*/
|
|
if (!GHOST_STATE(buf->b_hdr->b_state)) {
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
|
|
atomic_add_64(&hdr->b_state->arcs_size, size);
|
|
if (list_link_active(&hdr->b_arc_node)) {
|
|
ASSERT(refcount_is_zero(&hdr->b_refcnt));
|
|
atomic_add_64(&hdr->b_state->arcs_lsize[type], size);
|
|
}
|
|
/*
|
|
* If we are growing the cache, and we are adding anonymous
|
|
* data, and we have outgrown arc_p, update arc_p
|
|
*/
|
|
if (arc_size < arc_c && hdr->b_state == arc_anon &&
|
|
arc_anon->arcs_size + arc_mru->arcs_size > arc_p)
|
|
arc_p = MIN(arc_c, arc_p + size);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* This routine is called whenever a buffer is accessed.
|
|
* NOTE: the hash lock is dropped in this function.
|
|
*/
|
|
static void
|
|
arc_access(arc_buf_hdr_t *buf, kmutex_t *hash_lock)
|
|
{
|
|
clock_t now;
|
|
|
|
ASSERT(MUTEX_HELD(hash_lock));
|
|
|
|
if (buf->b_state == arc_anon) {
|
|
/*
|
|
* This buffer is not in the cache, and does not
|
|
* appear in our "ghost" list. Add the new buffer
|
|
* to the MRU state.
|
|
*/
|
|
|
|
ASSERT(buf->b_arc_access == 0);
|
|
buf->b_arc_access = ddi_get_lbolt();
|
|
DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, buf);
|
|
arc_change_state(arc_mru, buf, hash_lock);
|
|
|
|
} else if (buf->b_state == arc_mru) {
|
|
now = ddi_get_lbolt();
|
|
|
|
/*
|
|
* If this buffer is here because of a prefetch, then either:
|
|
* - clear the flag if this is a "referencing" read
|
|
* (any subsequent access will bump this into the MFU state).
|
|
* or
|
|
* - move the buffer to the head of the list if this is
|
|
* another prefetch (to make it less likely to be evicted).
|
|
*/
|
|
if ((buf->b_flags & ARC_PREFETCH) != 0) {
|
|
if (refcount_count(&buf->b_refcnt) == 0) {
|
|
ASSERT(list_link_active(&buf->b_arc_node));
|
|
} else {
|
|
buf->b_flags &= ~ARC_PREFETCH;
|
|
ARCSTAT_BUMP(arcstat_mru_hits);
|
|
}
|
|
buf->b_arc_access = now;
|
|
return;
|
|
}
|
|
|
|
/*
|
|
* This buffer has been "accessed" only once so far,
|
|
* but it is still in the cache. Move it to the MFU
|
|
* state.
|
|
*/
|
|
if (now > buf->b_arc_access + ARC_MINTIME) {
|
|
/*
|
|
* More than 125ms have passed since we
|
|
* instantiated this buffer. Move it to the
|
|
* most frequently used state.
|
|
*/
|
|
buf->b_arc_access = now;
|
|
DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf);
|
|
arc_change_state(arc_mfu, buf, hash_lock);
|
|
}
|
|
ARCSTAT_BUMP(arcstat_mru_hits);
|
|
} else if (buf->b_state == arc_mru_ghost) {
|
|
arc_state_t *new_state;
|
|
/*
|
|
* This buffer has been "accessed" recently, but
|
|
* was evicted from the cache. Move it to the
|
|
* MFU state.
|
|
*/
|
|
|
|
if (buf->b_flags & ARC_PREFETCH) {
|
|
new_state = arc_mru;
|
|
if (refcount_count(&buf->b_refcnt) > 0)
|
|
buf->b_flags &= ~ARC_PREFETCH;
|
|
DTRACE_PROBE1(new_state__mru, arc_buf_hdr_t *, buf);
|
|
} else {
|
|
new_state = arc_mfu;
|
|
DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf);
|
|
}
|
|
|
|
buf->b_arc_access = ddi_get_lbolt();
|
|
arc_change_state(new_state, buf, hash_lock);
|
|
|
|
ARCSTAT_BUMP(arcstat_mru_ghost_hits);
|
|
} else if (buf->b_state == arc_mfu) {
|
|
/*
|
|
* This buffer has been accessed more than once and is
|
|
* still in the cache. Keep it in the MFU state.
|
|
*
|
|
* NOTE: an add_reference() that occurred when we did
|
|
* the arc_read() will have kicked this off the list.
|
|
* If it was a prefetch, we will explicitly move it to
|
|
* the head of the list now.
|
|
*/
|
|
if ((buf->b_flags & ARC_PREFETCH) != 0) {
|
|
ASSERT(refcount_count(&buf->b_refcnt) == 0);
|
|
ASSERT(list_link_active(&buf->b_arc_node));
|
|
}
|
|
ARCSTAT_BUMP(arcstat_mfu_hits);
|
|
buf->b_arc_access = ddi_get_lbolt();
|
|
} else if (buf->b_state == arc_mfu_ghost) {
|
|
arc_state_t *new_state = arc_mfu;
|
|
/*
|
|
* This buffer has been accessed more than once but has
|
|
* been evicted from the cache. Move it back to the
|
|
* MFU state.
|
|
*/
|
|
|
|
if (buf->b_flags & ARC_PREFETCH) {
|
|
/*
|
|
* This is a prefetch access...
|
|
* move this block back to the MRU state.
|
|
*/
|
|
ASSERT3U(refcount_count(&buf->b_refcnt), ==, 0);
|
|
new_state = arc_mru;
|
|
}
|
|
|
|
buf->b_arc_access = ddi_get_lbolt();
|
|
DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf);
|
|
arc_change_state(new_state, buf, hash_lock);
|
|
|
|
ARCSTAT_BUMP(arcstat_mfu_ghost_hits);
|
|
} else if (buf->b_state == arc_l2c_only) {
|
|
/*
|
|
* This buffer is on the 2nd Level ARC.
|
|
*/
|
|
|
|
buf->b_arc_access = ddi_get_lbolt();
|
|
DTRACE_PROBE1(new_state__mfu, arc_buf_hdr_t *, buf);
|
|
arc_change_state(arc_mfu, buf, hash_lock);
|
|
} else {
|
|
ASSERT(!"invalid arc state");
|
|
}
|
|
}
|
|
|
|
/* a generic arc_done_func_t which you can use */
|
|
/* ARGSUSED */
|
|
void
|
|
arc_bcopy_func(zio_t *zio, arc_buf_t *buf, void *arg)
|
|
{
|
|
if (zio == NULL || zio->io_error == 0)
|
|
bcopy(buf->b_data, arg, buf->b_hdr->b_size);
|
|
VERIFY(arc_buf_remove_ref(buf, arg) == 1);
|
|
}
|
|
|
|
/* a generic arc_done_func_t */
|
|
void
|
|
arc_getbuf_func(zio_t *zio, arc_buf_t *buf, void *arg)
|
|
{
|
|
arc_buf_t **bufp = arg;
|
|
if (zio && zio->io_error) {
|
|
VERIFY(arc_buf_remove_ref(buf, arg) == 1);
|
|
*bufp = NULL;
|
|
} else {
|
|
*bufp = buf;
|
|
ASSERT(buf->b_data);
|
|
}
|
|
}
|
|
|
|
static void
|
|
arc_read_done(zio_t *zio)
|
|
{
|
|
arc_buf_hdr_t *hdr, *found;
|
|
arc_buf_t *buf;
|
|
arc_buf_t *abuf; /* buffer we're assigning to callback */
|
|
kmutex_t *hash_lock;
|
|
arc_callback_t *callback_list, *acb;
|
|
int freeable = FALSE;
|
|
|
|
buf = zio->io_private;
|
|
hdr = buf->b_hdr;
|
|
|
|
/*
|
|
* The hdr was inserted into hash-table and removed from lists
|
|
* prior to starting I/O. We should find this header, since
|
|
* it's in the hash table, and it should be legit since it's
|
|
* not possible to evict it during the I/O. The only possible
|
|
* reason for it not to be found is if we were freed during the
|
|
* read.
|
|
*/
|
|
found = buf_hash_find(hdr->b_spa, &hdr->b_dva, hdr->b_birth,
|
|
&hash_lock);
|
|
|
|
ASSERT((found == NULL && HDR_FREED_IN_READ(hdr) && hash_lock == NULL) ||
|
|
(found == hdr && DVA_EQUAL(&hdr->b_dva, BP_IDENTITY(zio->io_bp))) ||
|
|
(found == hdr && HDR_L2_READING(hdr)));
|
|
|
|
hdr->b_flags &= ~ARC_L2_EVICTED;
|
|
if (l2arc_noprefetch && (hdr->b_flags & ARC_PREFETCH))
|
|
hdr->b_flags &= ~ARC_L2CACHE;
|
|
|
|
/* byteswap if necessary */
|
|
callback_list = hdr->b_acb;
|
|
ASSERT(callback_list != NULL);
|
|
if (BP_SHOULD_BYTESWAP(zio->io_bp) && zio->io_error == 0) {
|
|
arc_byteswap_func_t *func = BP_GET_LEVEL(zio->io_bp) > 0 ?
|
|
byteswap_uint64_array :
|
|
dmu_ot[BP_GET_TYPE(zio->io_bp)].ot_byteswap;
|
|
func(buf->b_data, hdr->b_size);
|
|
}
|
|
|
|
arc_cksum_compute(buf, B_FALSE);
|
|
|
|
if (hash_lock && zio->io_error == 0 && hdr->b_state == arc_anon) {
|
|
/*
|
|
* Only call arc_access on anonymous buffers. This is because
|
|
* if we've issued an I/O for an evicted buffer, we've already
|
|
* called arc_access (to prevent any simultaneous readers from
|
|
* getting confused).
|
|
*/
|
|
arc_access(hdr, hash_lock);
|
|
}
|
|
|
|
/* create copies of the data buffer for the callers */
|
|
abuf = buf;
|
|
for (acb = callback_list; acb; acb = acb->acb_next) {
|
|
if (acb->acb_done) {
|
|
if (abuf == NULL)
|
|
abuf = arc_buf_clone(buf);
|
|
acb->acb_buf = abuf;
|
|
abuf = NULL;
|
|
}
|
|
}
|
|
hdr->b_acb = NULL;
|
|
hdr->b_flags &= ~ARC_IO_IN_PROGRESS;
|
|
ASSERT(!HDR_BUF_AVAILABLE(hdr));
|
|
if (abuf == buf) {
|
|
ASSERT(buf->b_efunc == NULL);
|
|
ASSERT(hdr->b_datacnt == 1);
|
|
hdr->b_flags |= ARC_BUF_AVAILABLE;
|
|
}
|
|
|
|
ASSERT(refcount_is_zero(&hdr->b_refcnt) || callback_list != NULL);
|
|
|
|
if (zio->io_error != 0) {
|
|
hdr->b_flags |= ARC_IO_ERROR;
|
|
if (hdr->b_state != arc_anon)
|
|
arc_change_state(arc_anon, hdr, hash_lock);
|
|
if (HDR_IN_HASH_TABLE(hdr))
|
|
buf_hash_remove(hdr);
|
|
freeable = refcount_is_zero(&hdr->b_refcnt);
|
|
}
|
|
|
|
/*
|
|
* Broadcast before we drop the hash_lock to avoid the possibility
|
|
* that the hdr (and hence the cv) might be freed before we get to
|
|
* the cv_broadcast().
|
|
*/
|
|
cv_broadcast(&hdr->b_cv);
|
|
|
|
if (hash_lock) {
|
|
mutex_exit(hash_lock);
|
|
} else {
|
|
/*
|
|
* This block was freed while we waited for the read to
|
|
* complete. It has been removed from the hash table and
|
|
* moved to the anonymous state (so that it won't show up
|
|
* in the cache).
|
|
*/
|
|
ASSERT3P(hdr->b_state, ==, arc_anon);
|
|
freeable = refcount_is_zero(&hdr->b_refcnt);
|
|
}
|
|
|
|
/* execute each callback and free its structure */
|
|
while ((acb = callback_list) != NULL) {
|
|
if (acb->acb_done)
|
|
acb->acb_done(zio, acb->acb_buf, acb->acb_private);
|
|
|
|
if (acb->acb_zio_dummy != NULL) {
|
|
acb->acb_zio_dummy->io_error = zio->io_error;
|
|
zio_nowait(acb->acb_zio_dummy);
|
|
}
|
|
|
|
callback_list = acb->acb_next;
|
|
kmem_free(acb, sizeof (arc_callback_t));
|
|
}
|
|
|
|
if (freeable)
|
|
arc_hdr_destroy(hdr);
|
|
}
|
|
|
|
/*
|
|
* "Read" the block block at the specified DVA (in bp) via the
|
|
* cache. If the block is found in the cache, invoke the provided
|
|
* callback immediately and return. Note that the `zio' parameter
|
|
* in the callback will be NULL in this case, since no IO was
|
|
* required. If the block is not in the cache pass the read request
|
|
* on to the spa with a substitute callback function, so that the
|
|
* requested block will be added to the cache.
|
|
*
|
|
* If a read request arrives for a block that has a read in-progress,
|
|
* either wait for the in-progress read to complete (and return the
|
|
* results); or, if this is a read with a "done" func, add a record
|
|
* to the read to invoke the "done" func when the read completes,
|
|
* and return; or just return.
|
|
*
|
|
* arc_read_done() will invoke all the requested "done" functions
|
|
* for readers of this block.
|
|
*
|
|
* Normal callers should use arc_read and pass the arc buffer and offset
|
|
* for the bp. But if you know you don't need locking, you can use
|
|
* arc_read_bp.
|
|
*/
|
|
int
|
|
arc_read(zio_t *pio, spa_t *spa, const blkptr_t *bp, arc_buf_t *pbuf,
|
|
arc_done_func_t *done, void *private, int priority, int zio_flags,
|
|
uint32_t *arc_flags, const zbookmark_t *zb)
|
|
{
|
|
int err;
|
|
|
|
if (pbuf == NULL) {
|
|
/*
|
|
* XXX This happens from traverse callback funcs, for
|
|
* the objset_phys_t block.
|
|
*/
|
|
return (arc_read_nolock(pio, spa, bp, done, private, priority,
|
|
zio_flags, arc_flags, zb));
|
|
}
|
|
|
|
ASSERT(!refcount_is_zero(&pbuf->b_hdr->b_refcnt));
|
|
ASSERT3U((char *)bp - (char *)pbuf->b_data, <, pbuf->b_hdr->b_size);
|
|
rw_enter(&pbuf->b_data_lock, RW_READER);
|
|
|
|
err = arc_read_nolock(pio, spa, bp, done, private, priority,
|
|
zio_flags, arc_flags, zb);
|
|
rw_exit(&pbuf->b_data_lock);
|
|
|
|
return (err);
|
|
}
|
|
|
|
int
|
|
arc_read_nolock(zio_t *pio, spa_t *spa, const blkptr_t *bp,
|
|
arc_done_func_t *done, void *private, int priority, int zio_flags,
|
|
uint32_t *arc_flags, const zbookmark_t *zb)
|
|
{
|
|
arc_buf_hdr_t *hdr;
|
|
arc_buf_t *buf = NULL;
|
|
kmutex_t *hash_lock;
|
|
zio_t *rzio;
|
|
uint64_t guid = spa_guid(spa);
|
|
|
|
top:
|
|
hdr = buf_hash_find(guid, BP_IDENTITY(bp), BP_PHYSICAL_BIRTH(bp),
|
|
&hash_lock);
|
|
if (hdr && hdr->b_datacnt > 0) {
|
|
|
|
*arc_flags |= ARC_CACHED;
|
|
|
|
if (HDR_IO_IN_PROGRESS(hdr)) {
|
|
|
|
if (*arc_flags & ARC_WAIT) {
|
|
cv_wait(&hdr->b_cv, hash_lock);
|
|
mutex_exit(hash_lock);
|
|
goto top;
|
|
}
|
|
ASSERT(*arc_flags & ARC_NOWAIT);
|
|
|
|
if (done) {
|
|
arc_callback_t *acb = NULL;
|
|
|
|
acb = kmem_zalloc(sizeof (arc_callback_t),
|
|
KM_PUSHPAGE);
|
|
acb->acb_done = done;
|
|
acb->acb_private = private;
|
|
if (pio != NULL)
|
|
acb->acb_zio_dummy = zio_null(pio,
|
|
spa, NULL, NULL, NULL, zio_flags);
|
|
|
|
ASSERT(acb->acb_done != NULL);
|
|
acb->acb_next = hdr->b_acb;
|
|
hdr->b_acb = acb;
|
|
add_reference(hdr, hash_lock, private);
|
|
mutex_exit(hash_lock);
|
|
return (0);
|
|
}
|
|
mutex_exit(hash_lock);
|
|
return (0);
|
|
}
|
|
|
|
ASSERT(hdr->b_state == arc_mru || hdr->b_state == arc_mfu);
|
|
|
|
if (done) {
|
|
add_reference(hdr, hash_lock, private);
|
|
/*
|
|
* If this block is already in use, create a new
|
|
* copy of the data so that we will be guaranteed
|
|
* that arc_release() will always succeed.
|
|
*/
|
|
buf = hdr->b_buf;
|
|
ASSERT(buf);
|
|
ASSERT(buf->b_data);
|
|
if (HDR_BUF_AVAILABLE(hdr)) {
|
|
ASSERT(buf->b_efunc == NULL);
|
|
hdr->b_flags &= ~ARC_BUF_AVAILABLE;
|
|
} else {
|
|
buf = arc_buf_clone(buf);
|
|
}
|
|
|
|
} else if (*arc_flags & ARC_PREFETCH &&
|
|
refcount_count(&hdr->b_refcnt) == 0) {
|
|
hdr->b_flags |= ARC_PREFETCH;
|
|
}
|
|
DTRACE_PROBE1(arc__hit, arc_buf_hdr_t *, hdr);
|
|
arc_access(hdr, hash_lock);
|
|
if (*arc_flags & ARC_L2CACHE)
|
|
hdr->b_flags |= ARC_L2CACHE;
|
|
mutex_exit(hash_lock);
|
|
ARCSTAT_BUMP(arcstat_hits);
|
|
ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH),
|
|
demand, prefetch, hdr->b_type != ARC_BUFC_METADATA,
|
|
data, metadata, hits);
|
|
|
|
if (done)
|
|
done(NULL, buf, private);
|
|
} else {
|
|
uint64_t size = BP_GET_LSIZE(bp);
|
|
arc_callback_t *acb;
|
|
vdev_t *vd = NULL;
|
|
uint64_t addr = -1;
|
|
boolean_t devw = B_FALSE;
|
|
|
|
if (hdr == NULL) {
|
|
/* this block is not in the cache */
|
|
arc_buf_hdr_t *exists;
|
|
arc_buf_contents_t type = BP_GET_BUFC_TYPE(bp);
|
|
buf = arc_buf_alloc(spa, size, private, type);
|
|
hdr = buf->b_hdr;
|
|
hdr->b_dva = *BP_IDENTITY(bp);
|
|
hdr->b_birth = BP_PHYSICAL_BIRTH(bp);
|
|
hdr->b_cksum0 = bp->blk_cksum.zc_word[0];
|
|
exists = buf_hash_insert(hdr, &hash_lock);
|
|
if (exists) {
|
|
/* somebody beat us to the hash insert */
|
|
mutex_exit(hash_lock);
|
|
buf_discard_identity(hdr);
|
|
(void) arc_buf_remove_ref(buf, private);
|
|
goto top; /* restart the IO request */
|
|
}
|
|
/* if this is a prefetch, we don't have a reference */
|
|
if (*arc_flags & ARC_PREFETCH) {
|
|
(void) remove_reference(hdr, hash_lock,
|
|
private);
|
|
hdr->b_flags |= ARC_PREFETCH;
|
|
}
|
|
if (*arc_flags & ARC_L2CACHE)
|
|
hdr->b_flags |= ARC_L2CACHE;
|
|
if (BP_GET_LEVEL(bp) > 0)
|
|
hdr->b_flags |= ARC_INDIRECT;
|
|
} else {
|
|
/* this block is in the ghost cache */
|
|
ASSERT(GHOST_STATE(hdr->b_state));
|
|
ASSERT(!HDR_IO_IN_PROGRESS(hdr));
|
|
ASSERT3U(refcount_count(&hdr->b_refcnt), ==, 0);
|
|
ASSERT(hdr->b_buf == NULL);
|
|
|
|
/* if this is a prefetch, we don't have a reference */
|
|
if (*arc_flags & ARC_PREFETCH)
|
|
hdr->b_flags |= ARC_PREFETCH;
|
|
else
|
|
add_reference(hdr, hash_lock, private);
|
|
if (*arc_flags & ARC_L2CACHE)
|
|
hdr->b_flags |= ARC_L2CACHE;
|
|
buf = kmem_cache_alloc(buf_cache, KM_PUSHPAGE);
|
|
buf->b_hdr = hdr;
|
|
buf->b_data = NULL;
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
buf->b_next = NULL;
|
|
hdr->b_buf = buf;
|
|
ASSERT(hdr->b_datacnt == 0);
|
|
hdr->b_datacnt = 1;
|
|
arc_get_data_buf(buf);
|
|
arc_access(hdr, hash_lock);
|
|
}
|
|
|
|
ASSERT(!GHOST_STATE(hdr->b_state));
|
|
|
|
acb = kmem_zalloc(sizeof (arc_callback_t), KM_PUSHPAGE);
|
|
acb->acb_done = done;
|
|
acb->acb_private = private;
|
|
|
|
ASSERT(hdr->b_acb == NULL);
|
|
hdr->b_acb = acb;
|
|
hdr->b_flags |= ARC_IO_IN_PROGRESS;
|
|
|
|
if (HDR_L2CACHE(hdr) && hdr->b_l2hdr != NULL &&
|
|
(vd = hdr->b_l2hdr->b_dev->l2ad_vdev) != NULL) {
|
|
devw = hdr->b_l2hdr->b_dev->l2ad_writing;
|
|
addr = hdr->b_l2hdr->b_daddr;
|
|
/*
|
|
* Lock out device removal.
|
|
*/
|
|
if (vdev_is_dead(vd) ||
|
|
!spa_config_tryenter(spa, SCL_L2ARC, vd, RW_READER))
|
|
vd = NULL;
|
|
}
|
|
|
|
mutex_exit(hash_lock);
|
|
|
|
ASSERT3U(hdr->b_size, ==, size);
|
|
DTRACE_PROBE4(arc__miss, arc_buf_hdr_t *, hdr, blkptr_t *, bp,
|
|
uint64_t, size, zbookmark_t *, zb);
|
|
ARCSTAT_BUMP(arcstat_misses);
|
|
ARCSTAT_CONDSTAT(!(hdr->b_flags & ARC_PREFETCH),
|
|
demand, prefetch, hdr->b_type != ARC_BUFC_METADATA,
|
|
data, metadata, misses);
|
|
|
|
if (vd != NULL && l2arc_ndev != 0 && !(l2arc_norw && devw)) {
|
|
/*
|
|
* Read from the L2ARC if the following are true:
|
|
* 1. The L2ARC vdev was previously cached.
|
|
* 2. This buffer still has L2ARC metadata.
|
|
* 3. This buffer isn't currently writing to the L2ARC.
|
|
* 4. The L2ARC entry wasn't evicted, which may
|
|
* also have invalidated the vdev.
|
|
* 5. This isn't prefetch and l2arc_noprefetch is set.
|
|
*/
|
|
if (hdr->b_l2hdr != NULL &&
|
|
!HDR_L2_WRITING(hdr) && !HDR_L2_EVICTED(hdr) &&
|
|
!(l2arc_noprefetch && HDR_PREFETCH(hdr))) {
|
|
l2arc_read_callback_t *cb;
|
|
|
|
DTRACE_PROBE1(l2arc__hit, arc_buf_hdr_t *, hdr);
|
|
ARCSTAT_BUMP(arcstat_l2_hits);
|
|
|
|
cb = kmem_zalloc(sizeof (l2arc_read_callback_t),
|
|
KM_PUSHPAGE);
|
|
cb->l2rcb_buf = buf;
|
|
cb->l2rcb_spa = spa;
|
|
cb->l2rcb_bp = *bp;
|
|
cb->l2rcb_zb = *zb;
|
|
cb->l2rcb_flags = zio_flags;
|
|
|
|
/*
|
|
* l2arc read. The SCL_L2ARC lock will be
|
|
* released by l2arc_read_done().
|
|
*/
|
|
rzio = zio_read_phys(pio, vd, addr, size,
|
|
buf->b_data, ZIO_CHECKSUM_OFF,
|
|
l2arc_read_done, cb, priority, zio_flags |
|
|
ZIO_FLAG_DONT_CACHE | ZIO_FLAG_CANFAIL |
|
|
ZIO_FLAG_DONT_PROPAGATE |
|
|
ZIO_FLAG_DONT_RETRY, B_FALSE);
|
|
DTRACE_PROBE2(l2arc__read, vdev_t *, vd,
|
|
zio_t *, rzio);
|
|
ARCSTAT_INCR(arcstat_l2_read_bytes, size);
|
|
|
|
if (*arc_flags & ARC_NOWAIT) {
|
|
zio_nowait(rzio);
|
|
return (0);
|
|
}
|
|
|
|
ASSERT(*arc_flags & ARC_WAIT);
|
|
if (zio_wait(rzio) == 0)
|
|
return (0);
|
|
|
|
/* l2arc read error; goto zio_read() */
|
|
} else {
|
|
DTRACE_PROBE1(l2arc__miss,
|
|
arc_buf_hdr_t *, hdr);
|
|
ARCSTAT_BUMP(arcstat_l2_misses);
|
|
if (HDR_L2_WRITING(hdr))
|
|
ARCSTAT_BUMP(arcstat_l2_rw_clash);
|
|
spa_config_exit(spa, SCL_L2ARC, vd);
|
|
}
|
|
} else {
|
|
if (vd != NULL)
|
|
spa_config_exit(spa, SCL_L2ARC, vd);
|
|
if (l2arc_ndev != 0) {
|
|
DTRACE_PROBE1(l2arc__miss,
|
|
arc_buf_hdr_t *, hdr);
|
|
ARCSTAT_BUMP(arcstat_l2_misses);
|
|
}
|
|
}
|
|
|
|
rzio = zio_read(pio, spa, bp, buf->b_data, size,
|
|
arc_read_done, buf, priority, zio_flags, zb);
|
|
|
|
if (*arc_flags & ARC_WAIT)
|
|
return (zio_wait(rzio));
|
|
|
|
ASSERT(*arc_flags & ARC_NOWAIT);
|
|
zio_nowait(rzio);
|
|
}
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
arc_set_callback(arc_buf_t *buf, arc_evict_func_t *func, void *private)
|
|
{
|
|
ASSERT(buf->b_hdr != NULL);
|
|
ASSERT(buf->b_hdr->b_state != arc_anon);
|
|
ASSERT(!refcount_is_zero(&buf->b_hdr->b_refcnt) || func == NULL);
|
|
ASSERT(buf->b_efunc == NULL);
|
|
ASSERT(!HDR_BUF_AVAILABLE(buf->b_hdr));
|
|
|
|
buf->b_efunc = func;
|
|
buf->b_private = private;
|
|
}
|
|
|
|
/*
|
|
* This is used by the DMU to let the ARC know that a buffer is
|
|
* being evicted, so the ARC should clean up. If this arc buf
|
|
* is not yet in the evicted state, it will be put there.
|
|
*/
|
|
int
|
|
arc_buf_evict(arc_buf_t *buf)
|
|
{
|
|
arc_buf_hdr_t *hdr;
|
|
kmutex_t *hash_lock;
|
|
arc_buf_t **bufp;
|
|
|
|
mutex_enter(&buf->b_evict_lock);
|
|
hdr = buf->b_hdr;
|
|
if (hdr == NULL) {
|
|
/*
|
|
* We are in arc_do_user_evicts().
|
|
*/
|
|
ASSERT(buf->b_data == NULL);
|
|
mutex_exit(&buf->b_evict_lock);
|
|
return (0);
|
|
} else if (buf->b_data == NULL) {
|
|
arc_buf_t copy = *buf; /* structure assignment */
|
|
/*
|
|
* We are on the eviction list; process this buffer now
|
|
* but let arc_do_user_evicts() do the reaping.
|
|
*/
|
|
buf->b_efunc = NULL;
|
|
mutex_exit(&buf->b_evict_lock);
|
|
VERIFY(copy.b_efunc(©) == 0);
|
|
return (1);
|
|
}
|
|
hash_lock = HDR_LOCK(hdr);
|
|
mutex_enter(hash_lock);
|
|
hdr = buf->b_hdr;
|
|
ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
|
|
|
|
ASSERT3U(refcount_count(&hdr->b_refcnt), <, hdr->b_datacnt);
|
|
ASSERT(hdr->b_state == arc_mru || hdr->b_state == arc_mfu);
|
|
|
|
/*
|
|
* Pull this buffer off of the hdr
|
|
*/
|
|
bufp = &hdr->b_buf;
|
|
while (*bufp != buf)
|
|
bufp = &(*bufp)->b_next;
|
|
*bufp = buf->b_next;
|
|
|
|
ASSERT(buf->b_data != NULL);
|
|
arc_buf_destroy(buf, FALSE, FALSE);
|
|
|
|
if (hdr->b_datacnt == 0) {
|
|
arc_state_t *old_state = hdr->b_state;
|
|
arc_state_t *evicted_state;
|
|
|
|
ASSERT(hdr->b_buf == NULL);
|
|
ASSERT(refcount_is_zero(&hdr->b_refcnt));
|
|
|
|
evicted_state =
|
|
(old_state == arc_mru) ? arc_mru_ghost : arc_mfu_ghost;
|
|
|
|
mutex_enter(&old_state->arcs_mtx);
|
|
mutex_enter(&evicted_state->arcs_mtx);
|
|
|
|
arc_change_state(evicted_state, hdr, hash_lock);
|
|
ASSERT(HDR_IN_HASH_TABLE(hdr));
|
|
hdr->b_flags |= ARC_IN_HASH_TABLE;
|
|
hdr->b_flags &= ~ARC_BUF_AVAILABLE;
|
|
|
|
mutex_exit(&evicted_state->arcs_mtx);
|
|
mutex_exit(&old_state->arcs_mtx);
|
|
}
|
|
mutex_exit(hash_lock);
|
|
mutex_exit(&buf->b_evict_lock);
|
|
|
|
VERIFY(buf->b_efunc(buf) == 0);
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
buf->b_hdr = NULL;
|
|
buf->b_next = NULL;
|
|
kmem_cache_free(buf_cache, buf);
|
|
return (1);
|
|
}
|
|
|
|
/*
|
|
* Release this buffer from the cache. This must be done
|
|
* after a read and prior to modifying the buffer contents.
|
|
* If the buffer has more than one reference, we must make
|
|
* a new hdr for the buffer.
|
|
*/
|
|
void
|
|
arc_release(arc_buf_t *buf, void *tag)
|
|
{
|
|
arc_buf_hdr_t *hdr;
|
|
kmutex_t *hash_lock = NULL;
|
|
l2arc_buf_hdr_t *l2hdr;
|
|
uint64_t buf_size = 0;
|
|
|
|
/*
|
|
* It would be nice to assert that if it's DMU metadata (level >
|
|
* 0 || it's the dnode file), then it must be syncing context.
|
|
* But we don't know that information at this level.
|
|
*/
|
|
|
|
mutex_enter(&buf->b_evict_lock);
|
|
hdr = buf->b_hdr;
|
|
|
|
/* this buffer is not on any list */
|
|
ASSERT(refcount_count(&hdr->b_refcnt) > 0);
|
|
|
|
if (hdr->b_state == arc_anon) {
|
|
/* this buffer is already released */
|
|
ASSERT(buf->b_efunc == NULL);
|
|
} else {
|
|
hash_lock = HDR_LOCK(hdr);
|
|
mutex_enter(hash_lock);
|
|
hdr = buf->b_hdr;
|
|
ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
|
|
}
|
|
|
|
l2hdr = hdr->b_l2hdr;
|
|
if (l2hdr) {
|
|
mutex_enter(&l2arc_buflist_mtx);
|
|
hdr->b_l2hdr = NULL;
|
|
buf_size = hdr->b_size;
|
|
}
|
|
|
|
/*
|
|
* Do we have more than one buf?
|
|
*/
|
|
if (hdr->b_datacnt > 1) {
|
|
arc_buf_hdr_t *nhdr;
|
|
arc_buf_t **bufp;
|
|
uint64_t blksz = hdr->b_size;
|
|
uint64_t spa = hdr->b_spa;
|
|
arc_buf_contents_t type = hdr->b_type;
|
|
uint32_t flags = hdr->b_flags;
|
|
|
|
ASSERT(hdr->b_buf != buf || buf->b_next != NULL);
|
|
/*
|
|
* Pull the data off of this hdr and attach it to
|
|
* a new anonymous hdr.
|
|
*/
|
|
(void) remove_reference(hdr, hash_lock, tag);
|
|
bufp = &hdr->b_buf;
|
|
while (*bufp != buf)
|
|
bufp = &(*bufp)->b_next;
|
|
*bufp = buf->b_next;
|
|
buf->b_next = NULL;
|
|
|
|
ASSERT3U(hdr->b_state->arcs_size, >=, hdr->b_size);
|
|
atomic_add_64(&hdr->b_state->arcs_size, -hdr->b_size);
|
|
if (refcount_is_zero(&hdr->b_refcnt)) {
|
|
uint64_t *size = &hdr->b_state->arcs_lsize[hdr->b_type];
|
|
ASSERT3U(*size, >=, hdr->b_size);
|
|
atomic_add_64(size, -hdr->b_size);
|
|
}
|
|
hdr->b_datacnt -= 1;
|
|
arc_cksum_verify(buf);
|
|
|
|
mutex_exit(hash_lock);
|
|
|
|
nhdr = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE);
|
|
nhdr->b_size = blksz;
|
|
nhdr->b_spa = spa;
|
|
nhdr->b_type = type;
|
|
nhdr->b_buf = buf;
|
|
nhdr->b_state = arc_anon;
|
|
nhdr->b_arc_access = 0;
|
|
nhdr->b_flags = flags & ARC_L2_WRITING;
|
|
nhdr->b_l2hdr = NULL;
|
|
nhdr->b_datacnt = 1;
|
|
nhdr->b_freeze_cksum = NULL;
|
|
(void) refcount_add(&nhdr->b_refcnt, tag);
|
|
buf->b_hdr = nhdr;
|
|
mutex_exit(&buf->b_evict_lock);
|
|
atomic_add_64(&arc_anon->arcs_size, blksz);
|
|
} else {
|
|
mutex_exit(&buf->b_evict_lock);
|
|
ASSERT(refcount_count(&hdr->b_refcnt) == 1);
|
|
ASSERT(!list_link_active(&hdr->b_arc_node));
|
|
ASSERT(!HDR_IO_IN_PROGRESS(hdr));
|
|
if (hdr->b_state != arc_anon)
|
|
arc_change_state(arc_anon, hdr, hash_lock);
|
|
hdr->b_arc_access = 0;
|
|
if (hash_lock)
|
|
mutex_exit(hash_lock);
|
|
|
|
buf_discard_identity(hdr);
|
|
arc_buf_thaw(buf);
|
|
}
|
|
buf->b_efunc = NULL;
|
|
buf->b_private = NULL;
|
|
|
|
if (l2hdr) {
|
|
list_remove(l2hdr->b_dev->l2ad_buflist, hdr);
|
|
kmem_free(l2hdr, sizeof (l2arc_buf_hdr_t));
|
|
ARCSTAT_INCR(arcstat_l2_size, -buf_size);
|
|
mutex_exit(&l2arc_buflist_mtx);
|
|
}
|
|
}
|
|
|
|
/*
|
|
* Release this buffer. If it does not match the provided BP, fill it
|
|
* with that block's contents.
|
|
*/
|
|
/* ARGSUSED */
|
|
int
|
|
arc_release_bp(arc_buf_t *buf, void *tag, blkptr_t *bp, spa_t *spa,
|
|
zbookmark_t *zb)
|
|
{
|
|
arc_release(buf, tag);
|
|
return (0);
|
|
}
|
|
|
|
int
|
|
arc_released(arc_buf_t *buf)
|
|
{
|
|
int released;
|
|
|
|
mutex_enter(&buf->b_evict_lock);
|
|
released = (buf->b_data != NULL && buf->b_hdr->b_state == arc_anon);
|
|
mutex_exit(&buf->b_evict_lock);
|
|
return (released);
|
|
}
|
|
|
|
int
|
|
arc_has_callback(arc_buf_t *buf)
|
|
{
|
|
int callback;
|
|
|
|
mutex_enter(&buf->b_evict_lock);
|
|
callback = (buf->b_efunc != NULL);
|
|
mutex_exit(&buf->b_evict_lock);
|
|
return (callback);
|
|
}
|
|
|
|
#ifdef ZFS_DEBUG
|
|
int
|
|
arc_referenced(arc_buf_t *buf)
|
|
{
|
|
int referenced;
|
|
|
|
mutex_enter(&buf->b_evict_lock);
|
|
referenced = (refcount_count(&buf->b_hdr->b_refcnt));
|
|
mutex_exit(&buf->b_evict_lock);
|
|
return (referenced);
|
|
}
|
|
#endif
|
|
|
|
static void
|
|
arc_write_ready(zio_t *zio)
|
|
{
|
|
arc_write_callback_t *callback = zio->io_private;
|
|
arc_buf_t *buf = callback->awcb_buf;
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
|
|
ASSERT(!refcount_is_zero(&buf->b_hdr->b_refcnt));
|
|
callback->awcb_ready(zio, buf, callback->awcb_private);
|
|
|
|
/*
|
|
* If the IO is already in progress, then this is a re-write
|
|
* attempt, so we need to thaw and re-compute the cksum.
|
|
* It is the responsibility of the callback to handle the
|
|
* accounting for any re-write attempt.
|
|
*/
|
|
if (HDR_IO_IN_PROGRESS(hdr)) {
|
|
mutex_enter(&hdr->b_freeze_lock);
|
|
if (hdr->b_freeze_cksum != NULL) {
|
|
kmem_free(hdr->b_freeze_cksum, sizeof (zio_cksum_t));
|
|
hdr->b_freeze_cksum = NULL;
|
|
}
|
|
mutex_exit(&hdr->b_freeze_lock);
|
|
}
|
|
arc_cksum_compute(buf, B_FALSE);
|
|
hdr->b_flags |= ARC_IO_IN_PROGRESS;
|
|
}
|
|
|
|
static void
|
|
arc_write_done(zio_t *zio)
|
|
{
|
|
arc_write_callback_t *callback = zio->io_private;
|
|
arc_buf_t *buf = callback->awcb_buf;
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
|
|
ASSERT(hdr->b_acb == NULL);
|
|
|
|
if (zio->io_error == 0) {
|
|
hdr->b_dva = *BP_IDENTITY(zio->io_bp);
|
|
hdr->b_birth = BP_PHYSICAL_BIRTH(zio->io_bp);
|
|
hdr->b_cksum0 = zio->io_bp->blk_cksum.zc_word[0];
|
|
} else {
|
|
ASSERT(BUF_EMPTY(hdr));
|
|
}
|
|
|
|
/*
|
|
* If the block to be written was all-zero, we may have
|
|
* compressed it away. In this case no write was performed
|
|
* so there will be no dva/birth/checksum. The buffer must
|
|
* therefore remain anonymous (and uncached).
|
|
*/
|
|
if (!BUF_EMPTY(hdr)) {
|
|
arc_buf_hdr_t *exists;
|
|
kmutex_t *hash_lock;
|
|
|
|
ASSERT(zio->io_error == 0);
|
|
|
|
arc_cksum_verify(buf);
|
|
|
|
exists = buf_hash_insert(hdr, &hash_lock);
|
|
if (exists) {
|
|
/*
|
|
* This can only happen if we overwrite for
|
|
* sync-to-convergence, because we remove
|
|
* buffers from the hash table when we arc_free().
|
|
*/
|
|
if (zio->io_flags & ZIO_FLAG_IO_REWRITE) {
|
|
if (!BP_EQUAL(&zio->io_bp_orig, zio->io_bp))
|
|
panic("bad overwrite, hdr=%p exists=%p",
|
|
(void *)hdr, (void *)exists);
|
|
ASSERT(refcount_is_zero(&exists->b_refcnt));
|
|
arc_change_state(arc_anon, exists, hash_lock);
|
|
mutex_exit(hash_lock);
|
|
arc_hdr_destroy(exists);
|
|
exists = buf_hash_insert(hdr, &hash_lock);
|
|
ASSERT3P(exists, ==, NULL);
|
|
} else {
|
|
/* Dedup */
|
|
ASSERT(hdr->b_datacnt == 1);
|
|
ASSERT(hdr->b_state == arc_anon);
|
|
ASSERT(BP_GET_DEDUP(zio->io_bp));
|
|
ASSERT(BP_GET_LEVEL(zio->io_bp) == 0);
|
|
}
|
|
}
|
|
hdr->b_flags &= ~ARC_IO_IN_PROGRESS;
|
|
/* if it's not anon, we are doing a scrub */
|
|
if (!exists && hdr->b_state == arc_anon)
|
|
arc_access(hdr, hash_lock);
|
|
mutex_exit(hash_lock);
|
|
} else {
|
|
hdr->b_flags &= ~ARC_IO_IN_PROGRESS;
|
|
}
|
|
|
|
ASSERT(!refcount_is_zero(&hdr->b_refcnt));
|
|
callback->awcb_done(zio, buf, callback->awcb_private);
|
|
|
|
kmem_free(callback, sizeof (arc_write_callback_t));
|
|
}
|
|
|
|
zio_t *
|
|
arc_write(zio_t *pio, spa_t *spa, uint64_t txg,
|
|
blkptr_t *bp, arc_buf_t *buf, boolean_t l2arc, const zio_prop_t *zp,
|
|
arc_done_func_t *ready, arc_done_func_t *done, void *private,
|
|
int priority, int zio_flags, const zbookmark_t *zb)
|
|
{
|
|
arc_buf_hdr_t *hdr = buf->b_hdr;
|
|
arc_write_callback_t *callback;
|
|
zio_t *zio;
|
|
|
|
ASSERT(ready != NULL);
|
|
ASSERT(done != NULL);
|
|
ASSERT(!HDR_IO_ERROR(hdr));
|
|
ASSERT((hdr->b_flags & ARC_IO_IN_PROGRESS) == 0);
|
|
ASSERT(hdr->b_acb == NULL);
|
|
if (l2arc)
|
|
hdr->b_flags |= ARC_L2CACHE;
|
|
callback = kmem_zalloc(sizeof (arc_write_callback_t), KM_SLEEP);
|
|
callback->awcb_ready = ready;
|
|
callback->awcb_done = done;
|
|
callback->awcb_private = private;
|
|
callback->awcb_buf = buf;
|
|
|
|
zio = zio_write(pio, spa, txg, bp, buf->b_data, hdr->b_size, zp,
|
|
arc_write_ready, arc_write_done, callback, priority, zio_flags, zb);
|
|
|
|
return (zio);
|
|
}
|
|
|
|
static int
|
|
arc_memory_throttle(uint64_t reserve, uint64_t inflight_data, uint64_t txg)
|
|
{
|
|
#ifdef _KERNEL
|
|
uint64_t available_memory = ptob(freemem);
|
|
static uint64_t page_load = 0;
|
|
static uint64_t last_txg = 0;
|
|
|
|
#if defined(__i386)
|
|
available_memory =
|
|
MIN(available_memory, vmem_size(heap_arena, VMEM_FREE));
|
|
#endif
|
|
if (available_memory >= zfs_write_limit_max)
|
|
return (0);
|
|
|
|
if (txg > last_txg) {
|
|
last_txg = txg;
|
|
page_load = 0;
|
|
}
|
|
/*
|
|
* If we are in pageout, we know that memory is already tight,
|
|
* the arc is already going to be evicting, so we just want to
|
|
* continue to let page writes occur as quickly as possible.
|
|
*/
|
|
if (curproc == proc_pageout) {
|
|
if (page_load > MAX(ptob(minfree), available_memory) / 4)
|
|
return (ERESTART);
|
|
/* Note: reserve is inflated, so we deflate */
|
|
page_load += reserve / 8;
|
|
return (0);
|
|
} else if (page_load > 0 && arc_reclaim_needed()) {
|
|
/* memory is low, delay before restarting */
|
|
ARCSTAT_INCR(arcstat_memory_throttle_count, 1);
|
|
return (EAGAIN);
|
|
}
|
|
page_load = 0;
|
|
|
|
if (arc_size > arc_c_min) {
|
|
uint64_t evictable_memory =
|
|
arc_mru->arcs_lsize[ARC_BUFC_DATA] +
|
|
arc_mru->arcs_lsize[ARC_BUFC_METADATA] +
|
|
arc_mfu->arcs_lsize[ARC_BUFC_DATA] +
|
|
arc_mfu->arcs_lsize[ARC_BUFC_METADATA];
|
|
available_memory += MIN(evictable_memory, arc_size - arc_c_min);
|
|
}
|
|
|
|
if (inflight_data > available_memory / 4) {
|
|
ARCSTAT_INCR(arcstat_memory_throttle_count, 1);
|
|
return (ERESTART);
|
|
}
|
|
#endif
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
arc_tempreserve_clear(uint64_t reserve)
|
|
{
|
|
atomic_add_64(&arc_tempreserve, -reserve);
|
|
ASSERT((int64_t)arc_tempreserve >= 0);
|
|
}
|
|
|
|
int
|
|
arc_tempreserve_space(uint64_t reserve, uint64_t txg)
|
|
{
|
|
int error;
|
|
uint64_t anon_size;
|
|
|
|
#ifdef ZFS_DEBUG
|
|
/*
|
|
* Once in a while, fail for no reason. Everything should cope.
|
|
*/
|
|
if (spa_get_random(10000) == 0) {
|
|
dprintf("forcing random failure\n");
|
|
return (ERESTART);
|
|
}
|
|
#endif
|
|
if (reserve > arc_c/4 && !arc_no_grow)
|
|
arc_c = MIN(arc_c_max, reserve * 4);
|
|
if (reserve > arc_c)
|
|
return (ENOMEM);
|
|
|
|
/*
|
|
* Don't count loaned bufs as in flight dirty data to prevent long
|
|
* network delays from blocking transactions that are ready to be
|
|
* assigned to a txg.
|
|
*/
|
|
anon_size = MAX((int64_t)(arc_anon->arcs_size - arc_loaned_bytes), 0);
|
|
|
|
/*
|
|
* Writes will, almost always, require additional memory allocations
|
|
* in order to compress/encrypt/etc the data. We therefor need to
|
|
* make sure that there is sufficient available memory for this.
|
|
*/
|
|
if ((error = arc_memory_throttle(reserve, anon_size, txg)))
|
|
return (error);
|
|
|
|
/*
|
|
* Throttle writes when the amount of dirty data in the cache
|
|
* gets too large. We try to keep the cache less than half full
|
|
* of dirty blocks so that our sync times don't grow too large.
|
|
* Note: if two requests come in concurrently, we might let them
|
|
* both succeed, when one of them should fail. Not a huge deal.
|
|
*/
|
|
|
|
if (reserve + arc_tempreserve + anon_size > arc_c / 2 &&
|
|
anon_size > arc_c / 4) {
|
|
dprintf("failing, arc_tempreserve=%lluK anon_meta=%lluK "
|
|
"anon_data=%lluK tempreserve=%lluK arc_c=%lluK\n",
|
|
arc_tempreserve>>10,
|
|
arc_anon->arcs_lsize[ARC_BUFC_METADATA]>>10,
|
|
arc_anon->arcs_lsize[ARC_BUFC_DATA]>>10,
|
|
reserve>>10, arc_c>>10);
|
|
return (ERESTART);
|
|
}
|
|
atomic_add_64(&arc_tempreserve, reserve);
|
|
return (0);
|
|
}
|
|
|
|
void
|
|
arc_init(void)
|
|
{
|
|
mutex_init(&arc_reclaim_thr_lock, NULL, MUTEX_DEFAULT, NULL);
|
|
cv_init(&arc_reclaim_thr_cv, NULL, CV_DEFAULT, NULL);
|
|
|
|
/* Convert seconds to clock ticks */
|
|
arc_min_prefetch_lifespan = 1 * hz;
|
|
|
|
/* Start out with 1/8 of all memory */
|
|
arc_c = physmem * PAGESIZE / 8;
|
|
|
|
#ifdef _KERNEL
|
|
/*
|
|
* On architectures where the physical memory can be larger
|
|
* than the addressable space (intel in 32-bit mode), we may
|
|
* need to limit the cache to 1/8 of VM size.
|
|
*/
|
|
arc_c = MIN(arc_c, vmem_size(heap_arena, VMEM_ALLOC | VMEM_FREE) / 8);
|
|
/*
|
|
* Register a shrinker to support synchronous (direct) memory
|
|
* reclaim from the arc. This is done to prevent kswapd from
|
|
* swapping out pages when it is preferable to shrink the arc.
|
|
*/
|
|
spl_register_shrinker(&arc_shrinker);
|
|
#endif
|
|
|
|
/* set min cache to 1/32 of all memory, or 64MB, whichever is more */
|
|
arc_c_min = MAX(arc_c / 4, 64<<20);
|
|
/* set max to 3/4 of all memory, or all but 1GB, whichever is more */
|
|
if (arc_c * 8 >= 1<<30)
|
|
arc_c_max = (arc_c * 8) - (1<<30);
|
|
else
|
|
arc_c_max = arc_c_min;
|
|
arc_c_max = MAX(arc_c * 6, arc_c_max);
|
|
|
|
/*
|
|
* Allow the tunables to override our calculations if they are
|
|
* reasonable (ie. over 64MB)
|
|
*/
|
|
if (zfs_arc_max > 64<<20 && zfs_arc_max < physmem * PAGESIZE)
|
|
arc_c_max = zfs_arc_max;
|
|
if (zfs_arc_min > 64<<20 && zfs_arc_min <= arc_c_max)
|
|
arc_c_min = zfs_arc_min;
|
|
|
|
arc_c = arc_c_max;
|
|
arc_p = (arc_c >> 1);
|
|
|
|
/* limit meta-data to 1/4 of the arc capacity */
|
|
arc_meta_limit = arc_c_max / 4;
|
|
arc_meta_max = 0;
|
|
|
|
/* Allow the tunable to override if it is reasonable */
|
|
if (zfs_arc_meta_limit > 0 && zfs_arc_meta_limit <= arc_c_max)
|
|
arc_meta_limit = zfs_arc_meta_limit;
|
|
|
|
if (arc_c_min < arc_meta_limit / 2 && zfs_arc_min == 0)
|
|
arc_c_min = arc_meta_limit / 2;
|
|
|
|
if (zfs_arc_grow_retry > 0)
|
|
arc_grow_retry = zfs_arc_grow_retry;
|
|
|
|
if (zfs_arc_shrink_shift > 0)
|
|
arc_shrink_shift = zfs_arc_shrink_shift;
|
|
|
|
if (zfs_arc_p_min_shift > 0)
|
|
arc_p_min_shift = zfs_arc_p_min_shift;
|
|
|
|
if (zfs_arc_reduce_dnlc_percent > 0)
|
|
arc_reduce_dnlc_percent = zfs_arc_reduce_dnlc_percent;
|
|
|
|
/* if kmem_flags are set, lets try to use less memory */
|
|
if (kmem_debugging())
|
|
arc_c = arc_c / 2;
|
|
if (arc_c < arc_c_min)
|
|
arc_c = arc_c_min;
|
|
|
|
arc_anon = &ARC_anon;
|
|
arc_mru = &ARC_mru;
|
|
arc_mru_ghost = &ARC_mru_ghost;
|
|
arc_mfu = &ARC_mfu;
|
|
arc_mfu_ghost = &ARC_mfu_ghost;
|
|
arc_l2c_only = &ARC_l2c_only;
|
|
arc_size = 0;
|
|
|
|
mutex_init(&arc_anon->arcs_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&arc_mru->arcs_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&arc_mru_ghost->arcs_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&arc_mfu->arcs_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&arc_mfu_ghost->arcs_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&arc_l2c_only->arcs_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
|
|
list_create(&arc_mru->arcs_list[ARC_BUFC_METADATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mru->arcs_list[ARC_BUFC_DATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mfu->arcs_list[ARC_BUFC_METADATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mfu->arcs_list[ARC_BUFC_DATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_l2c_only->arcs_list[ARC_BUFC_METADATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
list_create(&arc_l2c_only->arcs_list[ARC_BUFC_DATA],
|
|
sizeof (arc_buf_hdr_t), offsetof(arc_buf_hdr_t, b_arc_node));
|
|
|
|
buf_init();
|
|
|
|
arc_thread_exit = 0;
|
|
arc_eviction_list = NULL;
|
|
mutex_init(&arc_eviction_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
bzero(&arc_eviction_hdr, sizeof (arc_buf_hdr_t));
|
|
|
|
arc_ksp = kstat_create("zfs", 0, "arcstats", "misc", KSTAT_TYPE_NAMED,
|
|
sizeof (arc_stats) / sizeof (kstat_named_t), KSTAT_FLAG_VIRTUAL);
|
|
|
|
if (arc_ksp != NULL) {
|
|
arc_ksp->ks_data = &arc_stats;
|
|
kstat_install(arc_ksp);
|
|
}
|
|
|
|
(void) thread_create(NULL, 0, arc_reclaim_thread, NULL, 0, &p0,
|
|
TS_RUN, minclsyspri);
|
|
|
|
arc_dead = FALSE;
|
|
arc_warm = B_FALSE;
|
|
|
|
if (zfs_write_limit_max == 0)
|
|
zfs_write_limit_max = ptob(physmem) >> zfs_write_limit_shift;
|
|
else
|
|
zfs_write_limit_shift = 0;
|
|
mutex_init(&zfs_write_limit_lock, NULL, MUTEX_DEFAULT, NULL);
|
|
}
|
|
|
|
void
|
|
arc_fini(void)
|
|
{
|
|
mutex_enter(&arc_reclaim_thr_lock);
|
|
#ifdef _KERNEL
|
|
spl_unregister_shrinker(&arc_shrinker);
|
|
#endif /* _KERNEL */
|
|
|
|
arc_thread_exit = 1;
|
|
while (arc_thread_exit != 0)
|
|
cv_wait(&arc_reclaim_thr_cv, &arc_reclaim_thr_lock);
|
|
mutex_exit(&arc_reclaim_thr_lock);
|
|
|
|
arc_flush(NULL);
|
|
|
|
arc_dead = TRUE;
|
|
|
|
if (arc_ksp != NULL) {
|
|
kstat_delete(arc_ksp);
|
|
arc_ksp = NULL;
|
|
}
|
|
|
|
mutex_destroy(&arc_eviction_mtx);
|
|
mutex_destroy(&arc_reclaim_thr_lock);
|
|
cv_destroy(&arc_reclaim_thr_cv);
|
|
|
|
list_destroy(&arc_mru->arcs_list[ARC_BUFC_METADATA]);
|
|
list_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_METADATA]);
|
|
list_destroy(&arc_mfu->arcs_list[ARC_BUFC_METADATA]);
|
|
list_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_METADATA]);
|
|
list_destroy(&arc_mru->arcs_list[ARC_BUFC_DATA]);
|
|
list_destroy(&arc_mru_ghost->arcs_list[ARC_BUFC_DATA]);
|
|
list_destroy(&arc_mfu->arcs_list[ARC_BUFC_DATA]);
|
|
list_destroy(&arc_mfu_ghost->arcs_list[ARC_BUFC_DATA]);
|
|
|
|
mutex_destroy(&arc_anon->arcs_mtx);
|
|
mutex_destroy(&arc_mru->arcs_mtx);
|
|
mutex_destroy(&arc_mru_ghost->arcs_mtx);
|
|
mutex_destroy(&arc_mfu->arcs_mtx);
|
|
mutex_destroy(&arc_mfu_ghost->arcs_mtx);
|
|
mutex_destroy(&arc_l2c_only->arcs_mtx);
|
|
|
|
mutex_destroy(&zfs_write_limit_lock);
|
|
|
|
buf_fini();
|
|
|
|
ASSERT(arc_loaned_bytes == 0);
|
|
}
|
|
|
|
/*
|
|
* Level 2 ARC
|
|
*
|
|
* The level 2 ARC (L2ARC) is a cache layer in-between main memory and disk.
|
|
* It uses dedicated storage devices to hold cached data, which are populated
|
|
* using large infrequent writes. The main role of this cache is to boost
|
|
* the performance of random read workloads. The intended L2ARC devices
|
|
* include short-stroked disks, solid state disks, and other media with
|
|
* substantially faster read latency than disk.
|
|
*
|
|
* +-----------------------+
|
|
* | ARC |
|
|
* +-----------------------+
|
|
* | ^ ^
|
|
* | | |
|
|
* l2arc_feed_thread() arc_read()
|
|
* | | |
|
|
* | l2arc read |
|
|
* V | |
|
|
* +---------------+ |
|
|
* | L2ARC | |
|
|
* +---------------+ |
|
|
* | ^ |
|
|
* l2arc_write() | |
|
|
* | | |
|
|
* V | |
|
|
* +-------+ +-------+
|
|
* | vdev | | vdev |
|
|
* | cache | | cache |
|
|
* +-------+ +-------+
|
|
* +=========+ .-----.
|
|
* : L2ARC : |-_____-|
|
|
* : devices : | Disks |
|
|
* +=========+ `-_____-'
|
|
*
|
|
* Read requests are satisfied from the following sources, in order:
|
|
*
|
|
* 1) ARC
|
|
* 2) vdev cache of L2ARC devices
|
|
* 3) L2ARC devices
|
|
* 4) vdev cache of disks
|
|
* 5) disks
|
|
*
|
|
* Some L2ARC device types exhibit extremely slow write performance.
|
|
* To accommodate for this there are some significant differences between
|
|
* the L2ARC and traditional cache design:
|
|
*
|
|
* 1. There is no eviction path from the ARC to the L2ARC. Evictions from
|
|
* the ARC behave as usual, freeing buffers and placing headers on ghost
|
|
* lists. The ARC does not send buffers to the L2ARC during eviction as
|
|
* this would add inflated write latencies for all ARC memory pressure.
|
|
*
|
|
* 2. The L2ARC attempts to cache data from the ARC before it is evicted.
|
|
* It does this by periodically scanning buffers from the eviction-end of
|
|
* the MFU and MRU ARC lists, copying them to the L2ARC devices if they are
|
|
* not already there. It scans until a headroom of buffers is satisfied,
|
|
* which itself is a buffer for ARC eviction. The thread that does this is
|
|
* l2arc_feed_thread(), illustrated below; example sizes are included to
|
|
* provide a better sense of ratio than this diagram:
|
|
*
|
|
* head --> tail
|
|
* +---------------------+----------+
|
|
* ARC_mfu |:::::#:::::::::::::::|o#o###o###|-->. # already on L2ARC
|
|
* +---------------------+----------+ | o L2ARC eligible
|
|
* ARC_mru |:#:::::::::::::::::::|#o#ooo####|-->| : ARC buffer
|
|
* +---------------------+----------+ |
|
|
* 15.9 Gbytes ^ 32 Mbytes |
|
|
* headroom |
|
|
* l2arc_feed_thread()
|
|
* |
|
|
* l2arc write hand <--[oooo]--'
|
|
* | 8 Mbyte
|
|
* | write max
|
|
* V
|
|
* +==============================+
|
|
* L2ARC dev |####|#|###|###| |####| ... |
|
|
* +==============================+
|
|
* 32 Gbytes
|
|
*
|
|
* 3. If an ARC buffer is copied to the L2ARC but then hit instead of
|
|
* evicted, then the L2ARC has cached a buffer much sooner than it probably
|
|
* needed to, potentially wasting L2ARC device bandwidth and storage. It is
|
|
* safe to say that this is an uncommon case, since buffers at the end of
|
|
* the ARC lists have moved there due to inactivity.
|
|
*
|
|
* 4. If the ARC evicts faster than the L2ARC can maintain a headroom,
|
|
* then the L2ARC simply misses copying some buffers. This serves as a
|
|
* pressure valve to prevent heavy read workloads from both stalling the ARC
|
|
* with waits and clogging the L2ARC with writes. This also helps prevent
|
|
* the potential for the L2ARC to churn if it attempts to cache content too
|
|
* quickly, such as during backups of the entire pool.
|
|
*
|
|
* 5. After system boot and before the ARC has filled main memory, there are
|
|
* no evictions from the ARC and so the tails of the ARC_mfu and ARC_mru
|
|
* lists can remain mostly static. Instead of searching from tail of these
|
|
* lists as pictured, the l2arc_feed_thread() will search from the list heads
|
|
* for eligible buffers, greatly increasing its chance of finding them.
|
|
*
|
|
* The L2ARC device write speed is also boosted during this time so that
|
|
* the L2ARC warms up faster. Since there have been no ARC evictions yet,
|
|
* there are no L2ARC reads, and no fear of degrading read performance
|
|
* through increased writes.
|
|
*
|
|
* 6. Writes to the L2ARC devices are grouped and sent in-sequence, so that
|
|
* the vdev queue can aggregate them into larger and fewer writes. Each
|
|
* device is written to in a rotor fashion, sweeping writes through
|
|
* available space then repeating.
|
|
*
|
|
* 7. The L2ARC does not store dirty content. It never needs to flush
|
|
* write buffers back to disk based storage.
|
|
*
|
|
* 8. If an ARC buffer is written (and dirtied) which also exists in the
|
|
* L2ARC, the now stale L2ARC buffer is immediately dropped.
|
|
*
|
|
* The performance of the L2ARC can be tweaked by a number of tunables, which
|
|
* may be necessary for different workloads:
|
|
*
|
|
* l2arc_write_max max write bytes per interval
|
|
* l2arc_write_boost extra write bytes during device warmup
|
|
* l2arc_noprefetch skip caching prefetched buffers
|
|
* l2arc_headroom number of max device writes to precache
|
|
* l2arc_feed_secs seconds between L2ARC writing
|
|
*
|
|
* Tunables may be removed or added as future performance improvements are
|
|
* integrated, and also may become zpool properties.
|
|
*
|
|
* There are three key functions that control how the L2ARC warms up:
|
|
*
|
|
* l2arc_write_eligible() check if a buffer is eligible to cache
|
|
* l2arc_write_size() calculate how much to write
|
|
* l2arc_write_interval() calculate sleep delay between writes
|
|
*
|
|
* These three functions determine what to write, how much, and how quickly
|
|
* to send writes.
|
|
*/
|
|
|
|
static boolean_t
|
|
l2arc_write_eligible(uint64_t spa_guid, arc_buf_hdr_t *ab)
|
|
{
|
|
/*
|
|
* A buffer is *not* eligible for the L2ARC if it:
|
|
* 1. belongs to a different spa.
|
|
* 2. is already cached on the L2ARC.
|
|
* 3. has an I/O in progress (it may be an incomplete read).
|
|
* 4. is flagged not eligible (zfs property).
|
|
*/
|
|
if (ab->b_spa != spa_guid || ab->b_l2hdr != NULL ||
|
|
HDR_IO_IN_PROGRESS(ab) || !HDR_L2CACHE(ab))
|
|
return (B_FALSE);
|
|
|
|
return (B_TRUE);
|
|
}
|
|
|
|
static uint64_t
|
|
l2arc_write_size(l2arc_dev_t *dev)
|
|
{
|
|
uint64_t size;
|
|
|
|
size = dev->l2ad_write;
|
|
|
|
if (arc_warm == B_FALSE)
|
|
size += dev->l2ad_boost;
|
|
|
|
return (size);
|
|
|
|
}
|
|
|
|
static clock_t
|
|
l2arc_write_interval(clock_t began, uint64_t wanted, uint64_t wrote)
|
|
{
|
|
clock_t interval, next, now;
|
|
|
|
/*
|
|
* If the ARC lists are busy, increase our write rate; if the
|
|
* lists are stale, idle back. This is achieved by checking
|
|
* how much we previously wrote - if it was more than half of
|
|
* what we wanted, schedule the next write much sooner.
|
|
*/
|
|
if (l2arc_feed_again && wrote > (wanted / 2))
|
|
interval = (hz * l2arc_feed_min_ms) / 1000;
|
|
else
|
|
interval = hz * l2arc_feed_secs;
|
|
|
|
now = ddi_get_lbolt();
|
|
next = MAX(now, MIN(now + interval, began + interval));
|
|
|
|
return (next);
|
|
}
|
|
|
|
static void
|
|
l2arc_hdr_stat_add(void)
|
|
{
|
|
ARCSTAT_INCR(arcstat_l2_hdr_size, HDR_SIZE + L2HDR_SIZE);
|
|
ARCSTAT_INCR(arcstat_hdr_size, -HDR_SIZE);
|
|
}
|
|
|
|
static void
|
|
l2arc_hdr_stat_remove(void)
|
|
{
|
|
ARCSTAT_INCR(arcstat_l2_hdr_size, -(HDR_SIZE + L2HDR_SIZE));
|
|
ARCSTAT_INCR(arcstat_hdr_size, HDR_SIZE);
|
|
}
|
|
|
|
/*
|
|
* Cycle through L2ARC devices. This is how L2ARC load balances.
|
|
* If a device is returned, this also returns holding the spa config lock.
|
|
*/
|
|
static l2arc_dev_t *
|
|
l2arc_dev_get_next(void)
|
|
{
|
|
l2arc_dev_t *first, *next = NULL;
|
|
|
|
/*
|
|
* Lock out the removal of spas (spa_namespace_lock), then removal
|
|
* of cache devices (l2arc_dev_mtx). Once a device has been selected,
|
|
* both locks will be dropped and a spa config lock held instead.
|
|
*/
|
|
mutex_enter(&spa_namespace_lock);
|
|
mutex_enter(&l2arc_dev_mtx);
|
|
|
|
/* if there are no vdevs, there is nothing to do */
|
|
if (l2arc_ndev == 0)
|
|
goto out;
|
|
|
|
first = NULL;
|
|
next = l2arc_dev_last;
|
|
do {
|
|
/* loop around the list looking for a non-faulted vdev */
|
|
if (next == NULL) {
|
|
next = list_head(l2arc_dev_list);
|
|
} else {
|
|
next = list_next(l2arc_dev_list, next);
|
|
if (next == NULL)
|
|
next = list_head(l2arc_dev_list);
|
|
}
|
|
|
|
/* if we have come back to the start, bail out */
|
|
if (first == NULL)
|
|
first = next;
|
|
else if (next == first)
|
|
break;
|
|
|
|
} while (vdev_is_dead(next->l2ad_vdev));
|
|
|
|
/* if we were unable to find any usable vdevs, return NULL */
|
|
if (vdev_is_dead(next->l2ad_vdev))
|
|
next = NULL;
|
|
|
|
l2arc_dev_last = next;
|
|
|
|
out:
|
|
mutex_exit(&l2arc_dev_mtx);
|
|
|
|
/*
|
|
* Grab the config lock to prevent the 'next' device from being
|
|
* removed while we are writing to it.
|
|
*/
|
|
if (next != NULL)
|
|
spa_config_enter(next->l2ad_spa, SCL_L2ARC, next, RW_READER);
|
|
mutex_exit(&spa_namespace_lock);
|
|
|
|
return (next);
|
|
}
|
|
|
|
/*
|
|
* Free buffers that were tagged for destruction.
|
|
*/
|
|
static void
|
|
l2arc_do_free_on_write(void)
|
|
{
|
|
list_t *buflist;
|
|
l2arc_data_free_t *df, *df_prev;
|
|
|
|
mutex_enter(&l2arc_free_on_write_mtx);
|
|
buflist = l2arc_free_on_write;
|
|
|
|
for (df = list_tail(buflist); df; df = df_prev) {
|
|
df_prev = list_prev(buflist, df);
|
|
ASSERT(df->l2df_data != NULL);
|
|
ASSERT(df->l2df_func != NULL);
|
|
df->l2df_func(df->l2df_data, df->l2df_size);
|
|
list_remove(buflist, df);
|
|
kmem_free(df, sizeof (l2arc_data_free_t));
|
|
}
|
|
|
|
mutex_exit(&l2arc_free_on_write_mtx);
|
|
}
|
|
|
|
/*
|
|
* A write to a cache device has completed. Update all headers to allow
|
|
* reads from these buffers to begin.
|
|
*/
|
|
static void
|
|
l2arc_write_done(zio_t *zio)
|
|
{
|
|
l2arc_write_callback_t *cb;
|
|
l2arc_dev_t *dev;
|
|
list_t *buflist;
|
|
arc_buf_hdr_t *head, *ab, *ab_prev;
|
|
l2arc_buf_hdr_t *abl2;
|
|
kmutex_t *hash_lock;
|
|
|
|
cb = zio->io_private;
|
|
ASSERT(cb != NULL);
|
|
dev = cb->l2wcb_dev;
|
|
ASSERT(dev != NULL);
|
|
head = cb->l2wcb_head;
|
|
ASSERT(head != NULL);
|
|
buflist = dev->l2ad_buflist;
|
|
ASSERT(buflist != NULL);
|
|
DTRACE_PROBE2(l2arc__iodone, zio_t *, zio,
|
|
l2arc_write_callback_t *, cb);
|
|
|
|
if (zio->io_error != 0)
|
|
ARCSTAT_BUMP(arcstat_l2_writes_error);
|
|
|
|
mutex_enter(&l2arc_buflist_mtx);
|
|
|
|
/*
|
|
* All writes completed, or an error was hit.
|
|
*/
|
|
for (ab = list_prev(buflist, head); ab; ab = ab_prev) {
|
|
ab_prev = list_prev(buflist, ab);
|
|
|
|
hash_lock = HDR_LOCK(ab);
|
|
if (!mutex_tryenter(hash_lock)) {
|
|
/*
|
|
* This buffer misses out. It may be in a stage
|
|
* of eviction. Its ARC_L2_WRITING flag will be
|
|
* left set, denying reads to this buffer.
|
|
*/
|
|
ARCSTAT_BUMP(arcstat_l2_writes_hdr_miss);
|
|
continue;
|
|
}
|
|
|
|
if (zio->io_error != 0) {
|
|
/*
|
|
* Error - drop L2ARC entry.
|
|
*/
|
|
list_remove(buflist, ab);
|
|
abl2 = ab->b_l2hdr;
|
|
ab->b_l2hdr = NULL;
|
|
kmem_free(abl2, sizeof (l2arc_buf_hdr_t));
|
|
ARCSTAT_INCR(arcstat_l2_size, -ab->b_size);
|
|
}
|
|
|
|
/*
|
|
* Allow ARC to begin reads to this L2ARC entry.
|
|
*/
|
|
ab->b_flags &= ~ARC_L2_WRITING;
|
|
|
|
mutex_exit(hash_lock);
|
|
}
|
|
|
|
atomic_inc_64(&l2arc_writes_done);
|
|
list_remove(buflist, head);
|
|
kmem_cache_free(hdr_cache, head);
|
|
mutex_exit(&l2arc_buflist_mtx);
|
|
|
|
l2arc_do_free_on_write();
|
|
|
|
kmem_free(cb, sizeof (l2arc_write_callback_t));
|
|
}
|
|
|
|
/*
|
|
* A read to a cache device completed. Validate buffer contents before
|
|
* handing over to the regular ARC routines.
|
|
*/
|
|
static void
|
|
l2arc_read_done(zio_t *zio)
|
|
{
|
|
l2arc_read_callback_t *cb;
|
|
arc_buf_hdr_t *hdr;
|
|
arc_buf_t *buf;
|
|
kmutex_t *hash_lock;
|
|
int equal;
|
|
|
|
ASSERT(zio->io_vd != NULL);
|
|
ASSERT(zio->io_flags & ZIO_FLAG_DONT_PROPAGATE);
|
|
|
|
spa_config_exit(zio->io_spa, SCL_L2ARC, zio->io_vd);
|
|
|
|
cb = zio->io_private;
|
|
ASSERT(cb != NULL);
|
|
buf = cb->l2rcb_buf;
|
|
ASSERT(buf != NULL);
|
|
|
|
hash_lock = HDR_LOCK(buf->b_hdr);
|
|
mutex_enter(hash_lock);
|
|
hdr = buf->b_hdr;
|
|
ASSERT3P(hash_lock, ==, HDR_LOCK(hdr));
|
|
|
|
/*
|
|
* Check this survived the L2ARC journey.
|
|
*/
|
|
equal = arc_cksum_equal(buf);
|
|
if (equal && zio->io_error == 0 && !HDR_L2_EVICTED(hdr)) {
|
|
mutex_exit(hash_lock);
|
|
zio->io_private = buf;
|
|
zio->io_bp_copy = cb->l2rcb_bp; /* XXX fix in L2ARC 2.0 */
|
|
zio->io_bp = &zio->io_bp_copy; /* XXX fix in L2ARC 2.0 */
|
|
arc_read_done(zio);
|
|
} else {
|
|
mutex_exit(hash_lock);
|
|
/*
|
|
* Buffer didn't survive caching. Increment stats and
|
|
* reissue to the original storage device.
|
|
*/
|
|
if (zio->io_error != 0) {
|
|
ARCSTAT_BUMP(arcstat_l2_io_error);
|
|
} else {
|
|
zio->io_error = EIO;
|
|
}
|
|
if (!equal)
|
|
ARCSTAT_BUMP(arcstat_l2_cksum_bad);
|
|
|
|
/*
|
|
* If there's no waiter, issue an async i/o to the primary
|
|
* storage now. If there *is* a waiter, the caller must
|
|
* issue the i/o in a context where it's OK to block.
|
|
*/
|
|
if (zio->io_waiter == NULL) {
|
|
zio_t *pio = zio_unique_parent(zio);
|
|
|
|
ASSERT(!pio || pio->io_child_type == ZIO_CHILD_LOGICAL);
|
|
|
|
zio_nowait(zio_read(pio, cb->l2rcb_spa, &cb->l2rcb_bp,
|
|
buf->b_data, zio->io_size, arc_read_done, buf,
|
|
zio->io_priority, cb->l2rcb_flags, &cb->l2rcb_zb));
|
|
}
|
|
}
|
|
|
|
kmem_free(cb, sizeof (l2arc_read_callback_t));
|
|
}
|
|
|
|
/*
|
|
* This is the list priority from which the L2ARC will search for pages to
|
|
* cache. This is used within loops (0..3) to cycle through lists in the
|
|
* desired order. This order can have a significant effect on cache
|
|
* performance.
|
|
*
|
|
* Currently the metadata lists are hit first, MFU then MRU, followed by
|
|
* the data lists. This function returns a locked list, and also returns
|
|
* the lock pointer.
|
|
*/
|
|
static list_t *
|
|
l2arc_list_locked(int list_num, kmutex_t **lock)
|
|
{
|
|
list_t *list = NULL;
|
|
|
|
ASSERT(list_num >= 0 && list_num <= 3);
|
|
|
|
switch (list_num) {
|
|
case 0:
|
|
list = &arc_mfu->arcs_list[ARC_BUFC_METADATA];
|
|
*lock = &arc_mfu->arcs_mtx;
|
|
break;
|
|
case 1:
|
|
list = &arc_mru->arcs_list[ARC_BUFC_METADATA];
|
|
*lock = &arc_mru->arcs_mtx;
|
|
break;
|
|
case 2:
|
|
list = &arc_mfu->arcs_list[ARC_BUFC_DATA];
|
|
*lock = &arc_mfu->arcs_mtx;
|
|
break;
|
|
case 3:
|
|
list = &arc_mru->arcs_list[ARC_BUFC_DATA];
|
|
*lock = &arc_mru->arcs_mtx;
|
|
break;
|
|
}
|
|
|
|
ASSERT(!(MUTEX_HELD(*lock)));
|
|
mutex_enter(*lock);
|
|
return (list);
|
|
}
|
|
|
|
/*
|
|
* Evict buffers from the device write hand to the distance specified in
|
|
* bytes. This distance may span populated buffers, it may span nothing.
|
|
* This is clearing a region on the L2ARC device ready for writing.
|
|
* If the 'all' boolean is set, every buffer is evicted.
|
|
*/
|
|
static void
|
|
l2arc_evict(l2arc_dev_t *dev, uint64_t distance, boolean_t all)
|
|
{
|
|
list_t *buflist;
|
|
l2arc_buf_hdr_t *abl2;
|
|
arc_buf_hdr_t *ab, *ab_prev;
|
|
kmutex_t *hash_lock;
|
|
uint64_t taddr;
|
|
|
|
buflist = dev->l2ad_buflist;
|
|
|
|
if (buflist == NULL)
|
|
return;
|
|
|
|
if (!all && dev->l2ad_first) {
|
|
/*
|
|
* This is the first sweep through the device. There is
|
|
* nothing to evict.
|
|
*/
|
|
return;
|
|
}
|
|
|
|
if (dev->l2ad_hand >= (dev->l2ad_end - (2 * distance))) {
|
|
/*
|
|
* When nearing the end of the device, evict to the end
|
|
* before the device write hand jumps to the start.
|
|
*/
|
|
taddr = dev->l2ad_end;
|
|
} else {
|
|
taddr = dev->l2ad_hand + distance;
|
|
}
|
|
DTRACE_PROBE4(l2arc__evict, l2arc_dev_t *, dev, list_t *, buflist,
|
|
uint64_t, taddr, boolean_t, all);
|
|
|
|
top:
|
|
mutex_enter(&l2arc_buflist_mtx);
|
|
for (ab = list_tail(buflist); ab; ab = ab_prev) {
|
|
ab_prev = list_prev(buflist, ab);
|
|
|
|
hash_lock = HDR_LOCK(ab);
|
|
if (!mutex_tryenter(hash_lock)) {
|
|
/*
|
|
* Missed the hash lock. Retry.
|
|
*/
|
|
ARCSTAT_BUMP(arcstat_l2_evict_lock_retry);
|
|
mutex_exit(&l2arc_buflist_mtx);
|
|
mutex_enter(hash_lock);
|
|
mutex_exit(hash_lock);
|
|
goto top;
|
|
}
|
|
|
|
if (HDR_L2_WRITE_HEAD(ab)) {
|
|
/*
|
|
* We hit a write head node. Leave it for
|
|
* l2arc_write_done().
|
|
*/
|
|
list_remove(buflist, ab);
|
|
mutex_exit(hash_lock);
|
|
continue;
|
|
}
|
|
|
|
if (!all && ab->b_l2hdr != NULL &&
|
|
(ab->b_l2hdr->b_daddr > taddr ||
|
|
ab->b_l2hdr->b_daddr < dev->l2ad_hand)) {
|
|
/*
|
|
* We've evicted to the target address,
|
|
* or the end of the device.
|
|
*/
|
|
mutex_exit(hash_lock);
|
|
break;
|
|
}
|
|
|
|
if (HDR_FREE_IN_PROGRESS(ab)) {
|
|
/*
|
|
* Already on the path to destruction.
|
|
*/
|
|
mutex_exit(hash_lock);
|
|
continue;
|
|
}
|
|
|
|
if (ab->b_state == arc_l2c_only) {
|
|
ASSERT(!HDR_L2_READING(ab));
|
|
/*
|
|
* This doesn't exist in the ARC. Destroy.
|
|
* arc_hdr_destroy() will call list_remove()
|
|
* and decrement arcstat_l2_size.
|
|
*/
|
|
arc_change_state(arc_anon, ab, hash_lock);
|
|
arc_hdr_destroy(ab);
|
|
} else {
|
|
/*
|
|
* Invalidate issued or about to be issued
|
|
* reads, since we may be about to write
|
|
* over this location.
|
|
*/
|
|
if (HDR_L2_READING(ab)) {
|
|
ARCSTAT_BUMP(arcstat_l2_evict_reading);
|
|
ab->b_flags |= ARC_L2_EVICTED;
|
|
}
|
|
|
|
/*
|
|
* Tell ARC this no longer exists in L2ARC.
|
|
*/
|
|
if (ab->b_l2hdr != NULL) {
|
|
abl2 = ab->b_l2hdr;
|
|
ab->b_l2hdr = NULL;
|
|
kmem_free(abl2, sizeof (l2arc_buf_hdr_t));
|
|
ARCSTAT_INCR(arcstat_l2_size, -ab->b_size);
|
|
}
|
|
list_remove(buflist, ab);
|
|
|
|
/*
|
|
* This may have been leftover after a
|
|
* failed write.
|
|
*/
|
|
ab->b_flags &= ~ARC_L2_WRITING;
|
|
}
|
|
mutex_exit(hash_lock);
|
|
}
|
|
mutex_exit(&l2arc_buflist_mtx);
|
|
|
|
vdev_space_update(dev->l2ad_vdev, -(taddr - dev->l2ad_evict), 0, 0);
|
|
dev->l2ad_evict = taddr;
|
|
}
|
|
|
|
/*
|
|
* Find and write ARC buffers to the L2ARC device.
|
|
*
|
|
* An ARC_L2_WRITING flag is set so that the L2ARC buffers are not valid
|
|
* for reading until they have completed writing.
|
|
*/
|
|
static uint64_t
|
|
l2arc_write_buffers(spa_t *spa, l2arc_dev_t *dev, uint64_t target_sz)
|
|
{
|
|
arc_buf_hdr_t *ab, *ab_prev, *head;
|
|
l2arc_buf_hdr_t *hdrl2;
|
|
list_t *list;
|
|
uint64_t passed_sz, write_sz, buf_sz, headroom;
|
|
void *buf_data;
|
|
kmutex_t *hash_lock, *list_lock = NULL;
|
|
boolean_t have_lock, full;
|
|
l2arc_write_callback_t *cb;
|
|
zio_t *pio, *wzio;
|
|
uint64_t guid = spa_guid(spa);
|
|
int try;
|
|
|
|
ASSERT(dev->l2ad_vdev != NULL);
|
|
|
|
pio = NULL;
|
|
write_sz = 0;
|
|
full = B_FALSE;
|
|
head = kmem_cache_alloc(hdr_cache, KM_PUSHPAGE);
|
|
head->b_flags |= ARC_L2_WRITE_HEAD;
|
|
|
|
/*
|
|
* Copy buffers for L2ARC writing.
|
|
*/
|
|
mutex_enter(&l2arc_buflist_mtx);
|
|
for (try = 0; try <= 3; try++) {
|
|
list = l2arc_list_locked(try, &list_lock);
|
|
passed_sz = 0;
|
|
|
|
/*
|
|
* L2ARC fast warmup.
|
|
*
|
|
* Until the ARC is warm and starts to evict, read from the
|
|
* head of the ARC lists rather than the tail.
|
|
*/
|
|
headroom = target_sz * l2arc_headroom;
|
|
if (arc_warm == B_FALSE)
|
|
ab = list_head(list);
|
|
else
|
|
ab = list_tail(list);
|
|
|
|
for (; ab; ab = ab_prev) {
|
|
if (arc_warm == B_FALSE)
|
|
ab_prev = list_next(list, ab);
|
|
else
|
|
ab_prev = list_prev(list, ab);
|
|
|
|
hash_lock = HDR_LOCK(ab);
|
|
have_lock = MUTEX_HELD(hash_lock);
|
|
if (!have_lock && !mutex_tryenter(hash_lock)) {
|
|
/*
|
|
* Skip this buffer rather than waiting.
|
|
*/
|
|
continue;
|
|
}
|
|
|
|
passed_sz += ab->b_size;
|
|
if (passed_sz > headroom) {
|
|
/*
|
|
* Searched too far.
|
|
*/
|
|
mutex_exit(hash_lock);
|
|
break;
|
|
}
|
|
|
|
if (!l2arc_write_eligible(guid, ab)) {
|
|
mutex_exit(hash_lock);
|
|
continue;
|
|
}
|
|
|
|
if ((write_sz + ab->b_size) > target_sz) {
|
|
full = B_TRUE;
|
|
mutex_exit(hash_lock);
|
|
break;
|
|
}
|
|
|
|
if (pio == NULL) {
|
|
/*
|
|
* Insert a dummy header on the buflist so
|
|
* l2arc_write_done() can find where the
|
|
* write buffers begin without searching.
|
|
*/
|
|
list_insert_head(dev->l2ad_buflist, head);
|
|
|
|
cb = kmem_alloc(
|
|
sizeof (l2arc_write_callback_t), KM_SLEEP);
|
|
cb->l2wcb_dev = dev;
|
|
cb->l2wcb_head = head;
|
|
pio = zio_root(spa, l2arc_write_done, cb,
|
|
ZIO_FLAG_CANFAIL);
|
|
}
|
|
|
|
/*
|
|
* Create and add a new L2ARC header.
|
|
*/
|
|
hdrl2 = kmem_zalloc(sizeof (l2arc_buf_hdr_t), KM_SLEEP);
|
|
hdrl2->b_dev = dev;
|
|
hdrl2->b_daddr = dev->l2ad_hand;
|
|
|
|
ab->b_flags |= ARC_L2_WRITING;
|
|
ab->b_l2hdr = hdrl2;
|
|
list_insert_head(dev->l2ad_buflist, ab);
|
|
buf_data = ab->b_buf->b_data;
|
|
buf_sz = ab->b_size;
|
|
|
|
/*
|
|
* Compute and store the buffer cksum before
|
|
* writing. On debug the cksum is verified first.
|
|
*/
|
|
arc_cksum_verify(ab->b_buf);
|
|
arc_cksum_compute(ab->b_buf, B_TRUE);
|
|
|
|
mutex_exit(hash_lock);
|
|
|
|
wzio = zio_write_phys(pio, dev->l2ad_vdev,
|
|
dev->l2ad_hand, buf_sz, buf_data, ZIO_CHECKSUM_OFF,
|
|
NULL, NULL, ZIO_PRIORITY_ASYNC_WRITE,
|
|
ZIO_FLAG_CANFAIL, B_FALSE);
|
|
|
|
DTRACE_PROBE2(l2arc__write, vdev_t *, dev->l2ad_vdev,
|
|
zio_t *, wzio);
|
|
(void) zio_nowait(wzio);
|
|
|
|
/*
|
|
* Keep the clock hand suitably device-aligned.
|
|
*/
|
|
buf_sz = vdev_psize_to_asize(dev->l2ad_vdev, buf_sz);
|
|
|
|
write_sz += buf_sz;
|
|
dev->l2ad_hand += buf_sz;
|
|
}
|
|
|
|
mutex_exit(list_lock);
|
|
|
|
if (full == B_TRUE)
|
|
break;
|
|
}
|
|
mutex_exit(&l2arc_buflist_mtx);
|
|
|
|
if (pio == NULL) {
|
|
ASSERT3U(write_sz, ==, 0);
|
|
kmem_cache_free(hdr_cache, head);
|
|
return (0);
|
|
}
|
|
|
|
ASSERT3U(write_sz, <=, target_sz);
|
|
ARCSTAT_BUMP(arcstat_l2_writes_sent);
|
|
ARCSTAT_INCR(arcstat_l2_write_bytes, write_sz);
|
|
ARCSTAT_INCR(arcstat_l2_size, write_sz);
|
|
vdev_space_update(dev->l2ad_vdev, write_sz, 0, 0);
|
|
|
|
/*
|
|
* Bump device hand to the device start if it is approaching the end.
|
|
* l2arc_evict() will already have evicted ahead for this case.
|
|
*/
|
|
if (dev->l2ad_hand >= (dev->l2ad_end - target_sz)) {
|
|
vdev_space_update(dev->l2ad_vdev,
|
|
dev->l2ad_end - dev->l2ad_hand, 0, 0);
|
|
dev->l2ad_hand = dev->l2ad_start;
|
|
dev->l2ad_evict = dev->l2ad_start;
|
|
dev->l2ad_first = B_FALSE;
|
|
}
|
|
|
|
dev->l2ad_writing = B_TRUE;
|
|
(void) zio_wait(pio);
|
|
dev->l2ad_writing = B_FALSE;
|
|
|
|
return (write_sz);
|
|
}
|
|
|
|
/*
|
|
* This thread feeds the L2ARC at regular intervals. This is the beating
|
|
* heart of the L2ARC.
|
|
*/
|
|
static void
|
|
l2arc_feed_thread(void)
|
|
{
|
|
callb_cpr_t cpr;
|
|
l2arc_dev_t *dev;
|
|
spa_t *spa;
|
|
uint64_t size, wrote;
|
|
clock_t begin, next = ddi_get_lbolt();
|
|
|
|
CALLB_CPR_INIT(&cpr, &l2arc_feed_thr_lock, callb_generic_cpr, FTAG);
|
|
|
|
mutex_enter(&l2arc_feed_thr_lock);
|
|
|
|
while (l2arc_thread_exit == 0) {
|
|
CALLB_CPR_SAFE_BEGIN(&cpr);
|
|
(void) cv_timedwait_interruptible(&l2arc_feed_thr_cv,
|
|
&l2arc_feed_thr_lock, next);
|
|
CALLB_CPR_SAFE_END(&cpr, &l2arc_feed_thr_lock);
|
|
next = ddi_get_lbolt() + hz;
|
|
|
|
/*
|
|
* Quick check for L2ARC devices.
|
|
*/
|
|
mutex_enter(&l2arc_dev_mtx);
|
|
if (l2arc_ndev == 0) {
|
|
mutex_exit(&l2arc_dev_mtx);
|
|
continue;
|
|
}
|
|
mutex_exit(&l2arc_dev_mtx);
|
|
begin = ddi_get_lbolt();
|
|
|
|
/*
|
|
* This selects the next l2arc device to write to, and in
|
|
* doing so the next spa to feed from: dev->l2ad_spa. This
|
|
* will return NULL if there are now no l2arc devices or if
|
|
* they are all faulted.
|
|
*
|
|
* If a device is returned, its spa's config lock is also
|
|
* held to prevent device removal. l2arc_dev_get_next()
|
|
* will grab and release l2arc_dev_mtx.
|
|
*/
|
|
if ((dev = l2arc_dev_get_next()) == NULL)
|
|
continue;
|
|
|
|
spa = dev->l2ad_spa;
|
|
ASSERT(spa != NULL);
|
|
|
|
/*
|
|
* If the pool is read-only then force the feed thread to
|
|
* sleep a little longer.
|
|
*/
|
|
if (!spa_writeable(spa)) {
|
|
next = ddi_get_lbolt() + 5 * l2arc_feed_secs * hz;
|
|
spa_config_exit(spa, SCL_L2ARC, dev);
|
|
continue;
|
|
}
|
|
|
|
/*
|
|
* Avoid contributing to memory pressure.
|
|
*/
|
|
if (arc_reclaim_needed()) {
|
|
ARCSTAT_BUMP(arcstat_l2_abort_lowmem);
|
|
spa_config_exit(spa, SCL_L2ARC, dev);
|
|
continue;
|
|
}
|
|
|
|
ARCSTAT_BUMP(arcstat_l2_feeds);
|
|
|
|
size = l2arc_write_size(dev);
|
|
|
|
/*
|
|
* Evict L2ARC buffers that will be overwritten.
|
|
*/
|
|
l2arc_evict(dev, size, B_FALSE);
|
|
|
|
/*
|
|
* Write ARC buffers.
|
|
*/
|
|
wrote = l2arc_write_buffers(spa, dev, size);
|
|
|
|
/*
|
|
* Calculate interval between writes.
|
|
*/
|
|
next = l2arc_write_interval(begin, size, wrote);
|
|
spa_config_exit(spa, SCL_L2ARC, dev);
|
|
}
|
|
|
|
l2arc_thread_exit = 0;
|
|
cv_broadcast(&l2arc_feed_thr_cv);
|
|
CALLB_CPR_EXIT(&cpr); /* drops l2arc_feed_thr_lock */
|
|
thread_exit();
|
|
}
|
|
|
|
boolean_t
|
|
l2arc_vdev_present(vdev_t *vd)
|
|
{
|
|
l2arc_dev_t *dev;
|
|
|
|
mutex_enter(&l2arc_dev_mtx);
|
|
for (dev = list_head(l2arc_dev_list); dev != NULL;
|
|
dev = list_next(l2arc_dev_list, dev)) {
|
|
if (dev->l2ad_vdev == vd)
|
|
break;
|
|
}
|
|
mutex_exit(&l2arc_dev_mtx);
|
|
|
|
return (dev != NULL);
|
|
}
|
|
|
|
/*
|
|
* Add a vdev for use by the L2ARC. By this point the spa has already
|
|
* validated the vdev and opened it.
|
|
*/
|
|
void
|
|
l2arc_add_vdev(spa_t *spa, vdev_t *vd)
|
|
{
|
|
l2arc_dev_t *adddev;
|
|
|
|
ASSERT(!l2arc_vdev_present(vd));
|
|
|
|
/*
|
|
* Create a new l2arc device entry.
|
|
*/
|
|
adddev = kmem_zalloc(sizeof (l2arc_dev_t), KM_SLEEP);
|
|
adddev->l2ad_spa = spa;
|
|
adddev->l2ad_vdev = vd;
|
|
adddev->l2ad_write = l2arc_write_max;
|
|
adddev->l2ad_boost = l2arc_write_boost;
|
|
adddev->l2ad_start = VDEV_LABEL_START_SIZE;
|
|
adddev->l2ad_end = VDEV_LABEL_START_SIZE + vdev_get_min_asize(vd);
|
|
adddev->l2ad_hand = adddev->l2ad_start;
|
|
adddev->l2ad_evict = adddev->l2ad_start;
|
|
adddev->l2ad_first = B_TRUE;
|
|
adddev->l2ad_writing = B_FALSE;
|
|
list_link_init(&adddev->l2ad_node);
|
|
ASSERT3U(adddev->l2ad_write, >, 0);
|
|
|
|
/*
|
|
* This is a list of all ARC buffers that are still valid on the
|
|
* device.
|
|
*/
|
|
adddev->l2ad_buflist = kmem_zalloc(sizeof (list_t), KM_SLEEP);
|
|
list_create(adddev->l2ad_buflist, sizeof (arc_buf_hdr_t),
|
|
offsetof(arc_buf_hdr_t, b_l2node));
|
|
|
|
vdev_space_update(vd, 0, 0, adddev->l2ad_end - adddev->l2ad_hand);
|
|
|
|
/*
|
|
* Add device to global list
|
|
*/
|
|
mutex_enter(&l2arc_dev_mtx);
|
|
list_insert_head(l2arc_dev_list, adddev);
|
|
atomic_inc_64(&l2arc_ndev);
|
|
mutex_exit(&l2arc_dev_mtx);
|
|
}
|
|
|
|
/*
|
|
* Remove a vdev from the L2ARC.
|
|
*/
|
|
void
|
|
l2arc_remove_vdev(vdev_t *vd)
|
|
{
|
|
l2arc_dev_t *dev, *nextdev, *remdev = NULL;
|
|
|
|
/*
|
|
* Find the device by vdev
|
|
*/
|
|
mutex_enter(&l2arc_dev_mtx);
|
|
for (dev = list_head(l2arc_dev_list); dev; dev = nextdev) {
|
|
nextdev = list_next(l2arc_dev_list, dev);
|
|
if (vd == dev->l2ad_vdev) {
|
|
remdev = dev;
|
|
break;
|
|
}
|
|
}
|
|
ASSERT(remdev != NULL);
|
|
|
|
/*
|
|
* Remove device from global list
|
|
*/
|
|
list_remove(l2arc_dev_list, remdev);
|
|
l2arc_dev_last = NULL; /* may have been invalidated */
|
|
atomic_dec_64(&l2arc_ndev);
|
|
mutex_exit(&l2arc_dev_mtx);
|
|
|
|
/*
|
|
* Clear all buflists and ARC references. L2ARC device flush.
|
|
*/
|
|
l2arc_evict(remdev, 0, B_TRUE);
|
|
list_destroy(remdev->l2ad_buflist);
|
|
kmem_free(remdev->l2ad_buflist, sizeof (list_t));
|
|
kmem_free(remdev, sizeof (l2arc_dev_t));
|
|
}
|
|
|
|
void
|
|
l2arc_init(void)
|
|
{
|
|
l2arc_thread_exit = 0;
|
|
l2arc_ndev = 0;
|
|
l2arc_writes_sent = 0;
|
|
l2arc_writes_done = 0;
|
|
|
|
mutex_init(&l2arc_feed_thr_lock, NULL, MUTEX_DEFAULT, NULL);
|
|
cv_init(&l2arc_feed_thr_cv, NULL, CV_DEFAULT, NULL);
|
|
mutex_init(&l2arc_dev_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&l2arc_buflist_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
mutex_init(&l2arc_free_on_write_mtx, NULL, MUTEX_DEFAULT, NULL);
|
|
|
|
l2arc_dev_list = &L2ARC_dev_list;
|
|
l2arc_free_on_write = &L2ARC_free_on_write;
|
|
list_create(l2arc_dev_list, sizeof (l2arc_dev_t),
|
|
offsetof(l2arc_dev_t, l2ad_node));
|
|
list_create(l2arc_free_on_write, sizeof (l2arc_data_free_t),
|
|
offsetof(l2arc_data_free_t, l2df_list_node));
|
|
}
|
|
|
|
void
|
|
l2arc_fini(void)
|
|
{
|
|
/*
|
|
* This is called from dmu_fini(), which is called from spa_fini();
|
|
* Because of this, we can assume that all l2arc devices have
|
|
* already been removed when the pools themselves were removed.
|
|
*/
|
|
|
|
l2arc_do_free_on_write();
|
|
|
|
mutex_destroy(&l2arc_feed_thr_lock);
|
|
cv_destroy(&l2arc_feed_thr_cv);
|
|
mutex_destroy(&l2arc_dev_mtx);
|
|
mutex_destroy(&l2arc_buflist_mtx);
|
|
mutex_destroy(&l2arc_free_on_write_mtx);
|
|
|
|
list_destroy(l2arc_dev_list);
|
|
list_destroy(l2arc_free_on_write);
|
|
}
|
|
|
|
void
|
|
l2arc_start(void)
|
|
{
|
|
if (!(spa_mode_global & FWRITE))
|
|
return;
|
|
|
|
(void) thread_create(NULL, 0, l2arc_feed_thread, NULL, 0, &p0,
|
|
TS_RUN, minclsyspri);
|
|
}
|
|
|
|
void
|
|
l2arc_stop(void)
|
|
{
|
|
if (!(spa_mode_global & FWRITE))
|
|
return;
|
|
|
|
mutex_enter(&l2arc_feed_thr_lock);
|
|
cv_signal(&l2arc_feed_thr_cv); /* kick thread out of startup */
|
|
l2arc_thread_exit = 1;
|
|
while (l2arc_thread_exit != 0)
|
|
cv_wait(&l2arc_feed_thr_cv, &l2arc_feed_thr_lock);
|
|
mutex_exit(&l2arc_feed_thr_lock);
|
|
}
|
|
|
|
#if defined(_KERNEL) && defined(HAVE_SPL)
|
|
EXPORT_SYMBOL(arc_read);
|
|
EXPORT_SYMBOL(arc_buf_remove_ref);
|
|
EXPORT_SYMBOL(arc_getbuf_func);
|
|
|
|
module_param(zfs_arc_min, ulong, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_min, "Min arc size");
|
|
|
|
module_param(zfs_arc_max, ulong, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_max, "Max arc size");
|
|
|
|
module_param(zfs_arc_meta_limit, ulong, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_meta_limit, "Meta limit for arc size");
|
|
|
|
module_param(zfs_arc_reduce_dnlc_percent, int, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_reduce_dnlc_percent, "Meta reclaim percentage");
|
|
|
|
module_param(zfs_arc_grow_retry, int, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_grow_retry, "Seconds before growing arc size");
|
|
|
|
module_param(zfs_arc_shrink_shift, int, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_shrink_shift, "log2(fraction of arc to reclaim)");
|
|
|
|
module_param(zfs_arc_p_min_shift, int, 0444);
|
|
MODULE_PARM_DESC(zfs_arc_p_min_shift, "arc_c shift to calc min/max arc_p");
|
|
|
|
module_param(l2arc_write_max, ulong, 0444);
|
|
MODULE_PARM_DESC(l2arc_write_max, "Max write bytes per interval");
|
|
|
|
module_param(l2arc_write_boost, ulong, 0444);
|
|
MODULE_PARM_DESC(l2arc_write_boost, "Extra write bytes during device warmup");
|
|
|
|
module_param(l2arc_headroom, ulong, 0444);
|
|
MODULE_PARM_DESC(l2arc_headroom, "Number of max device writes to precache");
|
|
|
|
module_param(l2arc_feed_secs, ulong, 0444);
|
|
MODULE_PARM_DESC(l2arc_feed_secs, "Seconds between L2ARC writing");
|
|
|
|
module_param(l2arc_feed_min_ms, ulong, 0444);
|
|
MODULE_PARM_DESC(l2arc_feed_min_ms, "Min feed interval in milliseconds");
|
|
|
|
module_param(l2arc_noprefetch, int, 0444);
|
|
MODULE_PARM_DESC(l2arc_noprefetch, "Skip caching prefetched buffers");
|
|
|
|
module_param(l2arc_feed_again, int, 0444);
|
|
MODULE_PARM_DESC(l2arc_feed_again, "Turbo L2ARC warmup");
|
|
|
|
module_param(l2arc_norw, int, 0444);
|
|
MODULE_PARM_DESC(l2arc_norw, "No reads during writes");
|
|
|
|
#endif
|