mirror_zfs/include/sys/metaslab.h
Paul Dagnelie c81f1790e2 Metaslab max_size should be persisted while unloaded
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
2019-08-05 14:34:27 -07:00

145 lines
5.3 KiB
C

/*
* CDDL HEADER START
*
* The contents of this file are subject to the terms of the
* Common Development and Distribution License (the "License").
* You may not use this file except in compliance with the License.
*
* You can obtain a copy of the license at usr/src/OPENSOLARIS.LICENSE
* or http://www.opensolaris.org/os/licensing.
* See the License for the specific language governing permissions
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*
* When distributing Covered Code, include this CDDL HEADER in each
* file and include the License file at usr/src/OPENSOLARIS.LICENSE.
* If applicable, add the following below this CDDL HEADER, with the
* fields enclosed by brackets "[]" replaced with your own identifying
* information: Portions Copyright [yyyy] [name of copyright owner]
*
* CDDL HEADER END
*/
/*
* Copyright (c) 2005, 2010, Oracle and/or its affiliates. All rights reserved.
* Copyright (c) 2011, 2018 by Delphix. All rights reserved.
* Copyright (c) 2017, Intel Corporation.
*/
#ifndef _SYS_METASLAB_H
#define _SYS_METASLAB_H
#include <sys/spa.h>
#include <sys/space_map.h>
#include <sys/txg.h>
#include <sys/zio.h>
#include <sys/avl.h>
#ifdef __cplusplus
extern "C" {
#endif
typedef struct metaslab_ops {
uint64_t (*msop_alloc)(metaslab_t *, uint64_t);
} metaslab_ops_t;
extern metaslab_ops_t *zfs_metaslab_ops;
int metaslab_init(metaslab_group_t *, uint64_t, uint64_t, uint64_t,
metaslab_t **);
void metaslab_fini(metaslab_t *);
void metaslab_set_unflushed_txg(metaslab_t *, uint64_t, dmu_tx_t *);
void metaslab_set_estimated_condensed_size(metaslab_t *, uint64_t, dmu_tx_t *);
uint64_t metaslab_unflushed_txg(metaslab_t *);
uint64_t metaslab_estimated_condensed_size(metaslab_t *);
int metaslab_sort_by_flushed(const void *, const void *);
uint64_t metaslab_unflushed_changes_memused(metaslab_t *);
int metaslab_load(metaslab_t *);
void metaslab_potentially_unload(metaslab_t *, uint64_t);
void metaslab_unload(metaslab_t *);
boolean_t metaslab_flush(metaslab_t *, dmu_tx_t *);
uint64_t metaslab_allocated_space(metaslab_t *);
void metaslab_sync(metaslab_t *, uint64_t);
void metaslab_sync_done(metaslab_t *, uint64_t);
void metaslab_sync_reassess(metaslab_group_t *);
uint64_t metaslab_largest_allocatable(metaslab_t *);
/*
* metaslab alloc flags
*/
#define METASLAB_HINTBP_FAVOR 0x0
#define METASLAB_HINTBP_AVOID 0x1
#define METASLAB_GANG_HEADER 0x2
#define METASLAB_GANG_CHILD 0x4
#define METASLAB_ASYNC_ALLOC 0x8
#define METASLAB_DONT_THROTTLE 0x10
#define METASLAB_MUST_RESERVE 0x20
#define METASLAB_FASTWRITE 0x40
int metaslab_alloc(spa_t *, metaslab_class_t *, uint64_t,
blkptr_t *, int, uint64_t, blkptr_t *, int, zio_alloc_list_t *, zio_t *,
int);
int metaslab_alloc_dva(spa_t *, metaslab_class_t *, uint64_t,
dva_t *, int, dva_t *, uint64_t, int, zio_alloc_list_t *, int);
void metaslab_free(spa_t *, const blkptr_t *, uint64_t, boolean_t);
void metaslab_free_concrete(vdev_t *, uint64_t, uint64_t, boolean_t);
void metaslab_free_dva(spa_t *, const dva_t *, boolean_t);
void metaslab_free_impl_cb(uint64_t, vdev_t *, uint64_t, uint64_t, void *);
void metaslab_unalloc_dva(spa_t *, const dva_t *, uint64_t);
int metaslab_claim(spa_t *, const blkptr_t *, uint64_t);
int metaslab_claim_impl(vdev_t *, uint64_t, uint64_t, uint64_t);
void metaslab_check_free(spa_t *, const blkptr_t *);
void metaslab_fastwrite_mark(spa_t *, const blkptr_t *);
void metaslab_fastwrite_unmark(spa_t *, const blkptr_t *);
void metaslab_alloc_trace_init(void);
void metaslab_alloc_trace_fini(void);
void metaslab_trace_init(zio_alloc_list_t *);
void metaslab_trace_fini(zio_alloc_list_t *);
metaslab_class_t *metaslab_class_create(spa_t *, metaslab_ops_t *);
void metaslab_class_destroy(metaslab_class_t *);
int metaslab_class_validate(metaslab_class_t *);
void metaslab_class_histogram_verify(metaslab_class_t *);
uint64_t metaslab_class_fragmentation(metaslab_class_t *);
uint64_t metaslab_class_expandable_space(metaslab_class_t *);
boolean_t metaslab_class_throttle_reserve(metaslab_class_t *, int, int,
zio_t *, int);
void metaslab_class_throttle_unreserve(metaslab_class_t *, int, int, zio_t *);
uint64_t metaslab_class_get_alloc(metaslab_class_t *);
uint64_t metaslab_class_get_space(metaslab_class_t *);
uint64_t metaslab_class_get_dspace(metaslab_class_t *);
uint64_t metaslab_class_get_deferred(metaslab_class_t *);
void metaslab_space_update(vdev_t *, metaslab_class_t *,
int64_t, int64_t, int64_t);
metaslab_group_t *metaslab_group_create(metaslab_class_t *, vdev_t *, int);
void metaslab_group_destroy(metaslab_group_t *);
void metaslab_group_activate(metaslab_group_t *);
void metaslab_group_passivate(metaslab_group_t *);
boolean_t metaslab_group_initialized(metaslab_group_t *);
uint64_t metaslab_group_get_space(metaslab_group_t *);
void metaslab_group_histogram_verify(metaslab_group_t *);
uint64_t metaslab_group_fragmentation(metaslab_group_t *);
void metaslab_group_histogram_remove(metaslab_group_t *, metaslab_t *);
void metaslab_group_alloc_decrement(spa_t *, uint64_t, void *, int, int,
boolean_t);
void metaslab_group_alloc_verify(spa_t *, const blkptr_t *, void *, int);
void metaslab_recalculate_weight_and_sort(metaslab_t *);
void metaslab_disable(metaslab_t *);
void metaslab_enable(metaslab_t *, boolean_t);
extern int metaslab_debug_load;
#ifdef __cplusplus
}
#endif
#endif /* _SYS_METASLAB_H */