mirror_zfs/include/sys/dmu_zfetch.h
Paul Dagnelie f664f1ee7f Decrease contention on dn_struct_rwlock
Currently, sequential async write workloads spend a lot of time 
contending on the dn_struct_rwlock. This lock is responsible for 
protecting the entire block tree below it; this naturally results 
in some serialization during heavy write workloads. This can be 
resolved by having per-dbuf locking, which will allow multiple 
writers in the same object at the same time.

We introduce a new rwlock, the db_rwlock. This lock is responsible 
for protecting the contents of the dbuf that it is a part of; when 
reading a block pointer from a dbuf, you hold the lock as a reader. 
When writing data to a dbuf, you hold it as a writer. This allows 
multiple threads to write to different parts of a file at the same 
time.

Reviewed by: Brad Lewis <brad.lewis@delphix.com>
Reviewed by: Matt Ahrens matt@delphix.com
Reviewed by: George Wilson george.wilson@delphix.com
Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov>
Signed-off-by: Paul Dagnelie <pcd@delphix.com>
External-issue: DLPX-52564
External-issue: DLPX-53085
External-issue: DLPX-57384
Closes #8946
2019-07-08 13:18:50 -07:00

78 lines
2.0 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
* and limitations under the License.
*
* 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 2009 Sun Microsystems, Inc. All rights reserved.
* Use is subject to license terms.
*/
/*
* Copyright (c) 2014, 2017 by Delphix. All rights reserved.
*/
#ifndef _DMU_ZFETCH_H
#define _DMU_ZFETCH_H
#include <sys/zfs_context.h>
#ifdef __cplusplus
extern "C" {
#endif
extern unsigned long zfetch_array_rd_sz;
struct dnode; /* so we can reference dnode */
typedef struct zstream {
uint64_t zs_blkid; /* expect next access at this blkid */
uint64_t zs_pf_blkid; /* next block to prefetch */
/*
* We will next prefetch the L1 indirect block of this level-0
* block id.
*/
uint64_t zs_ipf_blkid;
kmutex_t zs_lock; /* protects stream */
hrtime_t zs_atime; /* time last prefetch issued */
list_node_t zs_node; /* link for zf_stream */
} zstream_t;
typedef struct zfetch {
krwlock_t zf_rwlock; /* protects zfetch structure */
list_t zf_stream; /* list of zstream_t's */
struct dnode *zf_dnode; /* dnode that owns this zfetch */
} zfetch_t;
void zfetch_init(void);
void zfetch_fini(void);
void dmu_zfetch_init(zfetch_t *, struct dnode *);
void dmu_zfetch_fini(zfetch_t *);
void dmu_zfetch(zfetch_t *, uint64_t, uint64_t, boolean_t,
boolean_t);
#ifdef __cplusplus
}
#endif
#endif /* _DMU_ZFETCH_H */