freebsd-nq/include/sys/multilist.h
Prakash Surya ca0bf58d65 Illumos 5497 - lock contention on arcs_mtx
Reviewed by: George Wilson <george.wilson@delphix.com>
Reviewed by: Matthew Ahrens <mahrens@delphix.com>
Reviewed by: Richard Elling <richard.elling@richardelling.com>
Approved by: Dan McDonald <danmcd@omniti.com>

Porting notes and other significant code changes:

The illumos 5368 patch (ARC should cache more metadata), which
was never picked up by ZoL, is mostly reverted by this patch.

Since ZoL relies on the kernel asynchronously calling the shrinker to
actually reap memory, the shrinker wakes up arc_reclaim_waiters_cv every
time it runs.

The arc_adapt_thread() function no longer calls arc_do_user_evicts()
since the newly-added arc_user_evicts_thread() calls it periodically.

Notable conflicting ZoL commits which conflicted with this patch or
whose effects are either duplicated or un-done by this patch:

    302f753 - Integrate ARC more tightly with Linux
    39e055c - Adjust arc_p based on "bytes" in arc_shrink
    f521ce1 - Allow "arc_p" to drop to zero or grow to "arc_c"
    77765b5 - Remove "arc_meta_used" from arc_adjust calculation
    94520ca - Prune metadata from ghost lists in arc_adjust_meta

Trace support for multilist_insert() and multilist_remove() has been
added and produces the following output:

    fio-12498 [077] .... 112936.448324: zfs_multilist__insert: ml { offset 240 numsublists 80 sublistidx 63 }
    fio-12498 [077] .... 112936.448347: zfs_multilist__remove: ml { offset 240 numsublists 80 sublistidx 29 }

The following arcstats have been removed:

    recycle_miss - Used by arcstat.py and arc_summary.py, both of which
    have been updated appropriately.

    l2_writes_hdr_miss

The following arcstats have been added:

    evict_not_enough - Number of times arc_evict_state() was unable to
    evict enough buffers to reach its target amount.

    evict_l2_skip - Number of times arc_evict_hdr() skipped eviction
    because it was being written to the l2arc.

    l2_writes_lock_retry - Replaces l2_writes_hdr_miss.  Number of times
    l2arc_write_done() failed to acquire hash_lock (and re-tries).

    arc_meta_min - Shows the value of the zfs_arc_meta_min module
    parameter (see below).

The "index" column of the "dbuf" kstat has been removed since it doesn't
have a direct analog in the new multilist scheme.  Additional multilist-
related stats could be added in the future but would likely require
extensions to the mulilist API.

The following module parameters have been added:

    zfs_arc_evict_batch_limit - Number of ARC headers to free per sub-list
    before moving on to the next sub-list.

    zfs_arc_meta_min - Enforce a floor on the amount of metadata in
    the ARC.

    zfs_arc_num_sublists_per_state - Number of multilist sub-lists per
    ARC state.

    zfs_arc_overflow_shift - Controls amount by which the ARC must exceed
    the target size to be considered "overflowing".

Ported-by: Tim Chase <tim@chase2k.com>
Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov
2015-06-11 10:27:25 -07:00

106 lines
3.1 KiB
C

/*
* CDDL HEADER START
*
* This file and its contents are supplied under the terms of the
* Common Development and Distribution License ("CDDL"), version 1.0.
* You may only use this file in accordance with the terms of version
* 1.0 of the CDDL.
*
* A full copy of the text of the CDDL should have accompanied this
* source. A copy of the CDDL is also available via the Internet at
* http://www.illumos.org/license/CDDL.
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2013, 2014 by Delphix. All rights reserved.
*/
#ifndef _SYS_MULTILIST_H
#define _SYS_MULTILIST_H
#include <sys/zfs_context.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef list_node_t multilist_node_t;
typedef struct multilist multilist_t;
typedef struct multilist_sublist multilist_sublist_t;
typedef unsigned int multilist_sublist_index_func_t(multilist_t *, void *);
struct multilist_sublist {
/*
* The mutex used internally to implement thread safe insertions
* and removals to this individual sublist. It can also be locked
* by a consumer using multilist_sublist_{lock,unlock}, which is
* useful if a consumer needs to traverse the list in a thread
* safe manner.
*/
kmutex_t mls_lock;
/*
* The actual list object containing all objects in this sublist.
*/
list_t mls_list;
/*
* Pad to cache line, in an effort to try and prevent cache line
* contention.
*/
} ____cacheline_aligned;
struct multilist {
/*
* This is used to get to the multilist_node_t structure given
* the void *object contained on the list.
*/
size_t ml_offset;
/*
* The number of sublists used internally by this multilist.
*/
uint64_t ml_num_sublists;
/*
* The array of pointers to the actual sublists.
*/
multilist_sublist_t *ml_sublists;
/*
* Pointer to function which determines the sublist to use
* when inserting and removing objects from this multilist.
* Please see the comment above multilist_create for details.
*/
multilist_sublist_index_func_t *ml_index_func;
};
void multilist_destroy(multilist_t *);
void multilist_create(multilist_t *, size_t, size_t, unsigned int,
multilist_sublist_index_func_t *);
void multilist_insert(multilist_t *, void *);
void multilist_remove(multilist_t *, void *);
int multilist_is_empty(multilist_t *);
unsigned int multilist_get_num_sublists(multilist_t *);
unsigned int multilist_get_random_index(multilist_t *);
multilist_sublist_t *multilist_sublist_lock(multilist_t *, unsigned int);
void multilist_sublist_unlock(multilist_sublist_t *);
void multilist_sublist_insert_head(multilist_sublist_t *, void *);
void multilist_sublist_insert_tail(multilist_sublist_t *, void *);
void multilist_sublist_move_forward(multilist_sublist_t *mls, void *obj);
void multilist_sublist_remove(multilist_sublist_t *, void *);
void *multilist_sublist_head(multilist_sublist_t *);
void *multilist_sublist_tail(multilist_sublist_t *);
void *multilist_sublist_next(multilist_sublist_t *, void *);
void *multilist_sublist_prev(multilist_sublist_t *, void *);
void multilist_link_init(multilist_node_t *);
int multilist_link_active(multilist_node_t *);
#ifdef __cplusplus
}
#endif
#endif /* _SYS_MULTILIST_H */