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6aa8c21a2a
- Make prefetch distance adaptive: up to 4MB prefetch doubles for every, hit same as before, but after that it grows by 1/8 every time the prefetch read does not complete in time to satisfy the demand. My tests show that 4MB is sufficient for wide NVMe pool to saturate single reader thread at 2.5GB/s, while new 64MB maximum allows the same thread to reach 1.5GB/s on wide HDD pool. Further distance increase may increase speed even more, but less dramatic and with higher latency. - Allow early reuse of inactive prefetch streams: streams that never saw hits can be reused immediately if there is a demand, while others can be reused after 1s of inactivity, starting with the oldest. After 2s of inactivity streams are deleted to free resources same as before. This allows by several times increase strided read performance on HDD pool in presence of simultaneous random reads, previously filling the zfetch_max_streams limit for seconds and so blocking most of prefetch. - Always issue intermediate indirect block reads with SYNC priority. Each of those reads if delayed for longer may delay up to 1024 other block prefetches, that may be not good for wide pools. Reviewed-by: Allan Jude <allan@klarasystems.com> Reviewed-by: Brian Behlendorf <behlendorf1@llnl.gov> Signed-off-by: Alexander Motin <mav@FreeBSD.org> Sponsored-By: iXsystems, Inc. Closes #13452
89 lines
2.7 KiB
C
89 lines
2.7 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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unsigned int zs_pf_dist; /* data prefetch distance in bytes */
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unsigned int zs_ipf_dist; /* L1 prefetch distance in bytes */
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uint64_t zs_pf_start; /* first data block to prefetch */
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uint64_t zs_pf_end; /* data block to prefetch up to */
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uint64_t zs_ipf_start; /* first data block to prefetch L1 */
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uint64_t zs_ipf_end; /* data block to prefetch L1 up to */
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list_node_t zs_node; /* link for zf_stream */
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hrtime_t zs_atime; /* time last prefetch issued */
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zfetch_t *zs_fetch; /* parent fetch */
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boolean_t zs_missed; /* stream saw cache misses */
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boolean_t zs_more; /* need more distant prefetch */
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zfs_refcount_t zs_callers; /* number of pending callers */
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/*
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* Number of stream references: dnode, callers and pending blocks.
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* The stream memory is freed when the number returns to zero.
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*/
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zfs_refcount_t zs_refs;
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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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zstream_t *dmu_zfetch_prepare(zfetch_t *, uint64_t, uint64_t, boolean_t,
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boolean_t);
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void dmu_zfetch_run(zstream_t *, boolean_t, boolean_t);
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void dmu_zfetch(zfetch_t *, uint64_t, uint64_t, boolean_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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