c81f1790e2
When we unload metaslabs today in ZFS, the cached max_size value is discarded. We instead use the histogram to determine whether or not we think we can satisfy an allocation from the metaslab. This can result in situations where, if we're doing I/Os of a size not aligned to a histogram bucket, a metaslab is loaded even though it cannot satisfy the allocation we think it can. For example, a metaslab with 16 entries in the 16k-32k bucket may have entirely 16kB entries. If we try to allocate a 24kB buffer, we will load that metaslab because we think it should be able to handle the allocation. Doing so is expensive in CPU time, disk reads, and average IO latency. This is exacerbated if the write being attempted is a sync write. This change makes ZFS cache the max_size after the metaslab is unloaded. If we ever get a free (or a coalesced group of frees) larger than the max_size, we will update it. Otherwise, we leave it as is. When attempting to allocate, we use the max_size as a lower bound, and respect it unless we are in try_hard. However, we do age the max_size out at some point, since we expect the actual max_size to increase as we do more frees. A more sophisticated algorithm here might be helpful, but this works reasonably well. Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Reviewed-by: Matt Ahrens <mahrens@delphix.com> Signed-off-by: Paul Dagnelie <pcd@delphix.com> Closes #9055
135 lines
4.9 KiB
C
135 lines
4.9 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 2009 Sun Microsystems, Inc. All rights reserved.
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* Use is subject to license terms.
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*/
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/*
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* Copyright (c) 2013, 2019 by Delphix. All rights reserved.
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*/
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#ifndef _SYS_RANGE_TREE_H
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#define _SYS_RANGE_TREE_H
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#include <sys/avl.h>
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#include <sys/dmu.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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#define RANGE_TREE_HISTOGRAM_SIZE 64
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typedef struct range_tree_ops range_tree_ops_t;
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/*
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* Note: the range_tree may not be accessed concurrently; consumers
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* must provide external locking if required.
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*/
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typedef struct range_tree {
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avl_tree_t rt_root; /* offset-ordered segment AVL tree */
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uint64_t rt_space; /* sum of all segments in the map */
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uint64_t rt_gap; /* allowable inter-segment gap */
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range_tree_ops_t *rt_ops;
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/* rt_avl_compare should only be set if rt_arg is an AVL tree */
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void *rt_arg;
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int (*rt_avl_compare)(const void *, const void *);
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/*
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* The rt_histogram maintains a histogram of ranges. Each bucket,
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* rt_histogram[i], contains the number of ranges whose size is:
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* 2^i <= size of range in bytes < 2^(i+1)
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*/
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uint64_t rt_histogram[RANGE_TREE_HISTOGRAM_SIZE];
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} range_tree_t;
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typedef struct range_seg {
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avl_node_t rs_node; /* AVL node */
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avl_node_t rs_pp_node; /* AVL picker-private node */
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uint64_t rs_start; /* starting offset of this segment */
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uint64_t rs_end; /* ending offset (non-inclusive) */
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uint64_t rs_fill; /* actual fill if gap mode is on */
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} range_seg_t;
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struct range_tree_ops {
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void (*rtop_create)(range_tree_t *rt, void *arg);
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void (*rtop_destroy)(range_tree_t *rt, void *arg);
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void (*rtop_add)(range_tree_t *rt, range_seg_t *rs, void *arg);
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void (*rtop_remove)(range_tree_t *rt, range_seg_t *rs, void *arg);
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void (*rtop_vacate)(range_tree_t *rt, void *arg);
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};
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typedef void range_tree_func_t(void *arg, uint64_t start, uint64_t size);
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void range_tree_init(void);
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void range_tree_fini(void);
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range_tree_t *range_tree_create_impl(range_tree_ops_t *ops, void *arg,
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int (*avl_compare) (const void *, const void *), uint64_t gap);
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range_tree_t *range_tree_create(range_tree_ops_t *ops, void *arg);
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void range_tree_destroy(range_tree_t *rt);
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boolean_t range_tree_contains(range_tree_t *rt, uint64_t start, uint64_t size);
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boolean_t range_tree_find_in(range_tree_t *rt, uint64_t start, uint64_t size,
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uint64_t *ostart, uint64_t *osize);
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void range_tree_verify_not_present(range_tree_t *rt,
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uint64_t start, uint64_t size);
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range_seg_t *range_tree_find(range_tree_t *rt, uint64_t start, uint64_t size);
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void range_tree_resize_segment(range_tree_t *rt, range_seg_t *rs,
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uint64_t newstart, uint64_t newsize);
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uint64_t range_tree_space(range_tree_t *rt);
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uint64_t range_tree_numsegs(range_tree_t *rt);
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boolean_t range_tree_is_empty(range_tree_t *rt);
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void range_tree_swap(range_tree_t **rtsrc, range_tree_t **rtdst);
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void range_tree_stat_verify(range_tree_t *rt);
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uint64_t range_tree_min(range_tree_t *rt);
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uint64_t range_tree_max(range_tree_t *rt);
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uint64_t range_tree_span(range_tree_t *rt);
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void range_tree_add(void *arg, uint64_t start, uint64_t size);
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void range_tree_remove(void *arg, uint64_t start, uint64_t size);
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void range_tree_remove_fill(range_tree_t *rt, uint64_t start, uint64_t size);
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void range_tree_adjust_fill(range_tree_t *rt, range_seg_t *rs, int64_t delta);
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void range_tree_clear(range_tree_t *rt, uint64_t start, uint64_t size);
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void range_tree_vacate(range_tree_t *rt, range_tree_func_t *func, void *arg);
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void range_tree_walk(range_tree_t *rt, range_tree_func_t *func, void *arg);
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range_seg_t *range_tree_first(range_tree_t *rt);
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void range_tree_remove_xor_add_segment(uint64_t start, uint64_t end,
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range_tree_t *removefrom, range_tree_t *addto);
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void range_tree_remove_xor_add(range_tree_t *rt, range_tree_t *removefrom,
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range_tree_t *addto);
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void rt_avl_create(range_tree_t *rt, void *arg);
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void rt_avl_destroy(range_tree_t *rt, void *arg);
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void rt_avl_add(range_tree_t *rt, range_seg_t *rs, void *arg);
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void rt_avl_remove(range_tree_t *rt, range_seg_t *rs, void *arg);
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void rt_avl_vacate(range_tree_t *rt, void *arg);
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extern struct range_tree_ops rt_avl_ops;
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#ifdef __cplusplus
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}
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#endif
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#endif /* _SYS_RANGE_TREE_H */
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