freebsd-skq/sys/cam/ctl/ctl_ser_table.c
Alexander Motin 9d9fd8b79f Micro-optimize OOA queue processing.
- Move ctl_get_cmd_entry() calls from every OOA traversal to when
  the requests first inserted, storing seridx in struct ctl_scsiio.
- Move some checks out of the loop in ctl_check_ooa().
- Replace checks for errors that can not happen with asserts.
- Transpose ctl_serialize_table, so that any OOA traversal accessed
  only one row (cache line).  Compact it from enum to uint8_t.
- Optimize static branch predictions in hottest places.

Due to O(n) nature on deep LUN queues this can be the hottest code
path in CTL, and additional 20% of IOPS I see in some 4KB I/O tests
are good to have in reserve.  About 50% of CPU time here according
to the profiles is now spent in two memory accesses per traversed
request in OOA.

Sponsored by:	iXsystems, Inc.
MFC after:	2 weeks
2021-02-27 10:40:24 -05:00

81 lines
4.1 KiB
C

/*-
* SPDX-License-Identifier: BSD-2-Clause-FreeBSD
*
* 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, row) into this table is the new command. The minor index */
/* (column) is the older, possibly already running, command. */
/* */
/* 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 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_SEQ /* Sequential check */
const static uint8_t
ctl_serialize_table[CTL_SERIDX_COUNT][CTL_SERIDX_COUNT] = {
/**>IDX_ :: 2nd:TUR RD WRT UNM SYN MDSN MDSL RQSN INQ RDCP RES LSNS FMT STR*/
/*TUR */{ pS, pS, pS, pS, pS, bK, bK, pS, pS, pS, bK, pS, pS, bK},
/*READ */{ pS, xS, xT, xO, pS, bK, bK, pS, pS, pS, bK, pS, bK, bK},
/*WRITE */{ pS, xT, xT, xO, pS, bK, bK, pS, pS, pS, bK, pS, bK, bK},
/*UNMAP */{ pS, bO, bO, pS, pS, bK, bK, pS, pS, pS, bK, pS, bK, bK},
/*SYNC */{ pS, pS, bO, pS, pS, bK, bK, pS, pS, pS, bK, pS, bK, bK},
/*MD_SNS */{ bK, bK, bK, bK, bK, pS, bK, pS, pS, pS, bK, pS, bK, bK},
/*MD_SEL */{ bK, bK, bK, bK, bK, bK, bK, pS, pS, pS, bK, bK, bK, bK},
/*RQ_SNS */{ bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, pS, bK},
/*INQ */{ pS, pS, pS, pS, pS, pS, pS, pS, pS, pS, pS, pS, pS, pS},
/*RD_CAP */{ pS, pS, pS, pS, pS, pS, pS, pS, pS, pS, bK, pS, bK, bK},
/*RES */{ bK, bK, bK, bK, bK, bK, bK, bK, pS, pS, bK, bK, bK, bK},
/*LOG_SNS */{ pS, pS, pS, pS, pS, pS, pS, pS, pS, pS, bK, pS, bK, bK},
/*FORMAT */{ bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, bK, bK},
/*START */{ bK, bK, bK, bK, bK, bK, bK, bK, bK, pS, bK, bK, bK, bK},
};