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Re-enable the old code in xlog.c that tried to use posix_fadvise(), so that

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we can get some buildfarm feedback about whether that function is still
problematic.  (Note that the planned async-preread patch will not really
prove anything one way or the other in buildfarm testing, since it will
be inactive with default GUC settings.)
This commit is contained in:
Tom Lane
2009-01-11 18:02:17 +00:00
parent a5d67a0a05
commit 1a37056a74
5 changed files with 29 additions and 26 deletions
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31
src/backend/access/transam/xlog.c
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@ -7,7 +7,7 @@
* Portions Copyright (c) 1996-2009, PostgreSQL Global Development Group
* Portions Copyright (c) 1994, Regents of the University of California
*
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.326 2009/01/01 17:23:36 momjian Exp $
* $PostgreSQL: pgsql/src/backend/access/transam/xlog.c,v 1.327 2009/01/11 18:02:17 tgl Exp $
*
*-------------------------------------------------------------------------
*/
@ -17,6 +17,7 @@
#include <ctype.h>
#include <signal.h>
#include <time.h>
#include <fcntl.h>
#include <sys/stat.h>
#include <sys/time.h>
#include <sys/wait.h>
@ -2435,30 +2436,18 @@ XLogFileClose(void)
{
Assert(openLogFile >= 0);
/*
* posix_fadvise is problematic on many platforms: on older x86 Linux it
* just dumps core, and there are reports of problems on PPC platforms as
* well. The following is therefore disabled for the time being. We could
* consider some kind of configure test to see if it's safe to use, but
* since we lack hard evidence that there's any useful performance gain to
* be had, spending time on that seems unprofitable for now.
*/
#ifdef NOT_USED
/*
* WAL segment files will not be re-read in normal operation, so we advise
* OS to release any cached pages. But do not do so if WAL archiving is
* active, because archiver process could use the cache to read the WAL
* segment.
*
* While O_DIRECT works for O_SYNC, posix_fadvise() works for fsync() and
* O_SYNC, and some platforms only have posix_fadvise().
* the OS to release any cached pages. But do not do so if WAL archiving
* is active, because archiver process could use the cache to read the WAL
* segment. Also, don't bother with it if we are using O_DIRECT, since
* the kernel is presumably not caching in that case.
*/
#if defined(HAVE_DECL_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED)
if (!XLogArchivingActive())
posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED);
#if defined(USE_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED)
if (!XLogArchivingActive() &&
(get_sync_bit(sync_method) & PG_O_DIRECT) == 0)
(void) posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED);
#endif
#endif /* NOT_USED */
if (close(openLogFile))
ereport(PANIC,