Date: Wed, 9 Jul 2003 15:13:00 -0500 (CDT) From: Dan Nelson <dnelson@allantgroup.com> To: FreeBSD-gnats-submit@FreeBSD.org Subject: bin/54276: pread/pwrite patches for libc db functions Message-ID: <200307092013.h69KD0ar094995@dan.emsphone.com> Resent-Message-ID: <200307092020.h69KKI4v042450@freefall.freebsd.org>
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>Number: 54276 >Category: bin >Synopsis: pread/pwrite patches for libc db functions >Confidential: no >Severity: non-critical >Priority: low >Responsible: freebsd-bugs >State: open >Quarter: >Keywords: >Date-Required: >Class: change-request >Submitter-Id: current-users >Arrival-Date: Wed Jul 09 13:20:18 PDT 2003 >Closed-Date: >Last-Modified: >Originator: Dan Nelson >Release: FreeBSD 5.1-CURRENT i386 >Organization: The Allant Group >Environment: System: FreeBSD dan.emsphone.com 5.1-CURRENT FreeBSD 5.1-CURRENT #276: Fri Jun 27 16:21:53 CDT 2003 dan@dan.emsphone.com:/usr/src/sys/i386/compile/DANSMP i386 >Description: The following patch replaces an lseek+read/write combo with a single pread/pwrite, cutting the number of syscalls by 1/2. All db I/O gets funnelled though mpool_get and mpool_write so these are the only functions that need changing. I've been running with this patch for 3 years and had forgotten about it :) Tested against >100mb btree indexes. >How-To-Repeat: >Fix: Index: mpool.c =================================================================== RCS file: /home/ncvs/src/lib/libc/db/mpool/mpool.c,v retrieving revision 1.10 diff -u -p -r1.10 mpool.c --- mpool.c 22 Mar 2002 21:52:01 -0000 1.10 +++ mpool.c 29 Mar 2002 18:42:00 -0000 @@ -207,9 +207,7 @@ mpool_get(mp, pgno, flags) ++mp->pageread; #endif off = mp->pagesize * pgno; - if (lseek(mp->fd, off, SEEK_SET) != off) - return (NULL); - if ((nr = _read(mp->fd, bp->page, mp->pagesize)) != mp->pagesize) { + if ((nr = pread(mp->fd, bp->page, mp->pagesize, off)) != mp->pagesize) { if (nr >= 0) errno = EFTYPE; return (NULL); @@ -381,9 +379,7 @@ mpool_write(mp, bp) (mp->pgout)(mp->pgcookie, bp->pgno, bp->page); off = mp->pagesize * bp->pgno; - if (lseek(mp->fd, off, SEEK_SET) != off) - return (RET_ERROR); - if (_write(mp->fd, bp->page, mp->pagesize) != mp->pagesize) + if (pwrite(mp->fd, bp->page, mp->pagesize, off) != mp->pagesize) return (RET_ERROR); bp->flags &= ~MPOOL_DIRTY; >Release-Note: >Audit-Trail: >Unformatted:
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