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5008 lock contention (rrw_exit) while running a read only load Reviewed by: Matthew Ahrens <matthew.ahrens@delphix.com> Reviewed by: George Wilson <george.wilson@delphix.com> Reviewed by: Alex Reece <alex.reece@delphix.com> Reviewed by: Christopher Siden <christopher.siden@delphix.com> Reviewed by: Richard Yao <ryao@gentoo.org> Reviewed by: Saso Kiselkov <skiselkov.ml@gmail.com> Approved by: Garrett D'Amore <garrett@damore.org> Porting notes: This patch ported perfectly cleanly to ZoL. During testing 100% cached small-block reads, extreme contention was noticed on rrl->rr_lock from rrw_exit() due to the frequent entering and leaving ZPL. Illumos picked up this patch from FreeBSD and it also helps under Linux. On a 1-minute 4K cached read test with 10 fio processes pinned to a single socket on a 4-socket (10 thread per socket) NUMA system, contentions on rrl->rr_lock were reduced from 508799 to 43085. Ported-by: Tim Chase <tim@chase2k.com> Signed-off-by: Brian Behlendorf <behlendorf1@llnl.gov> Closes #3555
116 lines
3.5 KiB
C
116 lines
3.5 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 2007 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) 2012 by Delphix. All rights reserved.
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*/
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#ifndef _SYS_RR_RW_LOCK_H
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#define _SYS_RR_RW_LOCK_H
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#ifdef __cplusplus
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extern "C" {
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#endif
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#include <sys/inttypes.h>
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#include <sys/zfs_context.h>
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#include <sys/refcount.h>
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/*
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* A reader-writer lock implementation that allows re-entrant reads, but
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* still gives writers priority on "new" reads.
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*
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* See rrwlock.c for more details about the implementation.
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*
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* Fields of the rrwlock_t structure:
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* - rr_lock: protects modification and reading of rrwlock_t fields
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* - rr_cv: cv for waking up readers or waiting writers
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* - rr_writer: thread id of the current writer
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* - rr_anon_rount: number of active anonymous readers
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* - rr_linked_rcount: total number of non-anonymous active readers
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* - rr_writer_wanted: a writer wants the lock
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*/
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typedef struct rrwlock {
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kmutex_t rr_lock;
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kcondvar_t rr_cv;
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kthread_t *rr_writer;
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refcount_t rr_anon_rcount;
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refcount_t rr_linked_rcount;
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boolean_t rr_writer_wanted;
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boolean_t rr_track_all;
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} rrwlock_t;
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/*
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* 'tag' is used in reference counting tracking. The
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* 'tag' must be the same in a rrw_enter() as in its
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* corresponding rrw_exit().
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*/
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void rrw_init(rrwlock_t *rrl, boolean_t track_all);
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void rrw_destroy(rrwlock_t *rrl);
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void rrw_enter(rrwlock_t *rrl, krw_t rw, void *tag);
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void rrw_enter_read(rrwlock_t *rrl, void *tag);
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void rrw_enter_read_prio(rrwlock_t *rrl, void *tag);
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void rrw_enter_write(rrwlock_t *rrl);
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void rrw_exit(rrwlock_t *rrl, void *tag);
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boolean_t rrw_held(rrwlock_t *rrl, krw_t rw);
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void rrw_tsd_destroy(void *arg);
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#define RRW_READ_HELD(x) rrw_held(x, RW_READER)
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#define RRW_WRITE_HELD(x) rrw_held(x, RW_WRITER)
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#define RRW_LOCK_HELD(x) \
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(rrw_held(x, RW_WRITER) || rrw_held(x, RW_READER))
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/*
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* A reader-mostly lock implementation, tuning above reader-writer locks
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* for hightly parallel read acquisitions, pessimizing write acquisitions.
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*
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* This should be a prime number. See comment in rrwlock.c near
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* RRM_TD_LOCK() for details.
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*/
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#define RRM_NUM_LOCKS 17
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typedef struct rrmlock {
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rrwlock_t locks[RRM_NUM_LOCKS];
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} rrmlock_t;
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void rrm_init(rrmlock_t *rrl, boolean_t track_all);
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void rrm_destroy(rrmlock_t *rrl);
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void rrm_enter(rrmlock_t *rrl, krw_t rw, void *tag);
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void rrm_enter_read(rrmlock_t *rrl, void *tag);
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void rrm_enter_write(rrmlock_t *rrl);
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void rrm_exit(rrmlock_t *rrl, void *tag);
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boolean_t rrm_held(rrmlock_t *rrl, krw_t rw);
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#define RRM_READ_HELD(x) rrm_held(x, RW_READER)
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#define RRM_WRITE_HELD(x) rrm_held(x, RW_WRITER)
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#define RRM_LOCK_HELD(x) \
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(rrm_held(x, RW_WRITER) || rrm_held(x, RW_READER))
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#ifdef __cplusplus
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}
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#endif
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#endif /* _SYS_RR_RW_LOCK_H */
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