bfbfc4a3cb
Technically read requests can be executed in any order or simultaneously since they are not changing any data. But ZFS prefetcher goes crasy when it receives consecutive requests from different threads. Since prefetcher works on level of separate blocks, instead of two consecutive 128K requests it may receive 32 8K requests in mixed order. This patch is more workaround then a real fix, and it does not fix all of prefetcher problems, but it improves sequential read speed by 3-4x times in some configurations. On the other side it may hurt performance if some backing store has no prefetch, that is why it is disabled by default for raw devices. MFC after: 2 weeks
82 lines
4.2 KiB
C
82 lines
4.2 KiB
C
/*-
|
|
* Copyright (c) 2003 Silicon Graphics International Corp.
|
|
* All rights reserved.
|
|
*
|
|
* Redistribution and use in source and binary forms, with or without
|
|
* modification, are permitted provided that the following conditions
|
|
* are met:
|
|
* 1. Redistributions of source code must retain the above copyright
|
|
* notice, this list of conditions, and the following disclaimer,
|
|
* without modification.
|
|
* 2. Redistributions in binary form must reproduce at minimum a disclaimer
|
|
* substantially similar to the "NO WARRANTY" disclaimer below
|
|
* ("Disclaimer") and any redistribution must be conditioned upon
|
|
* including a substantially similar Disclaimer requirement for further
|
|
* binary redistribution.
|
|
*
|
|
* NO WARRANTY
|
|
* THIS SOFTWARE IS PROVIDED BY THE COPYRIGHT HOLDERS AND CONTRIBUTORS
|
|
* "AS IS" AND ANY EXPRESS OR IMPLIED WARRANTIES, INCLUDING, BUT NOT
|
|
* LIMITED TO, THE IMPLIED WARRANTIES OF MERCHANTIBILITY AND FITNESS FOR
|
|
* A PARTICULAR PURPOSE ARE DISCLAIMED. IN NO EVENT SHALL THE COPYRIGHT
|
|
* HOLDERS OR CONTRIBUTORS BE LIABLE FOR SPECIAL, EXEMPLARY, OR CONSEQUENTIAL
|
|
* DAMAGES (INCLUDING, BUT NOT LIMITED TO, PROCUREMENT OF SUBSTITUTE GOODS
|
|
* OR SERVICES; LOSS OF USE, DATA, OR PROFITS; OR BUSINESS INTERRUPTION)
|
|
* HOWEVER CAUSED AND ON ANY THEORY OF LIABILITY, WHETHER IN CONTRACT,
|
|
* STRICT LIABILITY, OR TORT (INCLUDING NEGLIGENCE OR OTHERWISE) ARISING
|
|
* IN ANY WAY OUT OF THE USE OF THIS SOFTWARE, EVEN IF ADVISED OF THE
|
|
* POSSIBILITY OF SUCH DAMAGES.
|
|
*
|
|
* $Id: //depot/users/kenm/FreeBSD-test2/sys/cam/ctl/ctl_ser_table.c#1 $
|
|
* $FreeBSD$
|
|
*/
|
|
|
|
/*
|
|
* CAM Target Layer command serialization table.
|
|
*
|
|
* Author: Kim Le
|
|
*/
|
|
|
|
/****************************************************************************/
|
|
/* TABLE ctlSerTbl */
|
|
/* */
|
|
/* The matrix which drives the serialization algorithm. The major index */
|
|
/* (the first) into this table is the command being checked and the minor */
|
|
/* index is the command against which the first command is being checked. */
|
|
/* i.e., the major index (row) command is ahead of the minor index command */
|
|
/* (column) in the queue. This allows the code to optimize by capturing */
|
|
/* the result of the first indexing operation into a pointer. */
|
|
/* */
|
|
/* Whenever a new value is added to the IDX_T type, this matrix must be */
|
|
/* expanded by one row AND one column -- Because of this, some effort */
|
|
/* should be made to re-use the indexes whenever possible. */
|
|
/* */
|
|
/****************************************************************************/
|
|
|
|
#define sK CTL_SER_SKIP /* Skip */
|
|
#define pS CTL_SER_PASS /* Pass */
|
|
#define bK CTL_SER_BLOCK /* Blocked */
|
|
#define bO CTL_SER_BLOCKOPT /* Optional block */
|
|
#define xT CTL_SER_EXTENT /* Extent check */
|
|
#define xO CTL_SER_EXTENTOPT /* Optional extent check */
|
|
#define xS CTL_SER_EXTENTSEQ /* Sequential extent check */
|
|
|
|
static ctl_serialize_action
|
|
ctl_serialize_table[CTL_SERIDX_COUNT][CTL_SERIDX_COUNT] = {
|
|
/**>IDX_ :: 2nd:TUR RD WRT UNM MDSN MDSL RQSN INQ RDCP RES LSNS FMT STR*/
|
|
/*TUR */{ pS, pS, pS, pS, bK, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*READ */{ pS, xS, xT, bO, bK, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*WRITE */{ pS, xT, xT, bO, bK, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*UNMAP */{ pS, xO, xO, pS, bK, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*MD_SNS */{ bK, bK, bK, bK, pS, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*MD_SEL */{ bK, bK, bK, bK, bK, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*RQ_SNS */{ pS, pS, pS, pS, pS, pS, bK, pS, pS, bK, pS, bK, bK},
|
|
/*INQ */{ pS, pS, pS, pS, pS, pS, bK, pS, pS, pS, pS, bK, bK},
|
|
/*RD_CAP */{ pS, pS, pS, pS, pS, pS, bK, pS, pS, pS, pS, bK, pS},
|
|
/*RES */{ bK, bK, bK, bK, bK, bK, bK, pS, bK, bK, bK, bK, bK},
|
|
/*LOG_SNS */{ pS, pS, pS, pS, pS, bK, bK, pS, pS, bK, pS, bK, bK},
|
|
/*FORMAT */{ pS, bK, bK, bK, bK, bK, pS, pS, bK, bK, bK, bK, bK},
|
|
/*START */{ bK, bK, bK, bK, bK, bK, bK, pS, bK, bK, bK, bK, bK},
|
|
};
|
|
|