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af20b97078
The current dmu_zfetch code implicitly assumes that I/Os complete within min_sec_reap seconds. With async dmu and a readonly workload (and thus no exponential backoff in operations from the "write throttle") such as L2ARC rebuild it is possible to saturate the drives with I/O requests. These are then effectively compounded with prefetch requests. This change reference counts streams and prevents them from being recycled after their min_sec_reap timeout if they still have outstanding I/Os. Reviewed-by: Alexander Motin <mav@FreeBSD.org> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Matt Macy <mmacy@FreeBSD.org> Closes #10900
82 lines
2.2 KiB
C
82 lines
2.2 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) 2014, 2017 by Delphix. All rights reserved.
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*/
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#ifndef _DMU_ZFETCH_H
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#define _DMU_ZFETCH_H
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#include <sys/zfs_context.h>
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#ifdef __cplusplus
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extern "C" {
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#endif
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extern unsigned long zfetch_array_rd_sz;
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struct dnode; /* so we can reference dnode */
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typedef struct zfetch {
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kmutex_t zf_lock; /* protects zfetch structure */
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list_t zf_stream; /* list of zstream_t's */
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struct dnode *zf_dnode; /* dnode that owns this zfetch */
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int zf_numstreams; /* number of zstream_t's */
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} zfetch_t;
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typedef struct zstream {
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uint64_t zs_blkid; /* expect next access at this blkid */
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uint64_t zs_pf_blkid; /* next block to prefetch */
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/*
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* We will next prefetch the L1 indirect block of this level-0
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* block id.
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*/
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uint64_t zs_ipf_blkid;
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kmutex_t zs_lock; /* protects stream */
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hrtime_t zs_atime; /* time last prefetch issued */
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hrtime_t zs_start_time; /* start of last prefetch */
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list_node_t zs_node; /* link for zf_stream */
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zfetch_t *zs_fetch; /* parent fetch */
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zfs_refcount_t zs_blocks; /* number of pending blocks in the stream */
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} zstream_t;
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void zfetch_init(void);
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void zfetch_fini(void);
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void dmu_zfetch_init(zfetch_t *, struct dnode *);
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void dmu_zfetch_fini(zfetch_t *);
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void dmu_zfetch(zfetch_t *, uint64_t, uint64_t, boolean_t,
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boolean_t);
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#ifdef __cplusplus
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}
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#endif
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#endif /* _DMU_ZFETCH_H */
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