From 1a37056a74e273085c39bb88cba48797695c067e Mon Sep 17 00:00:00 2001
From: Tom Lane <tgl@sss.pgh.pa.us>
Date: Sun, 11 Jan 2009 18:02:17 +0000
Subject: [PATCH] Re-enable the old code in xlog.c that tried to use
posix_fadvise(), so that 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.)
---
configure | 3 ++-
configure.in | 4 ++--
src/backend/access/transam/xlog.c | 33 +++++++++++--------------------
src/include/pg_config.h.in | 3 +++
src/include/pg_config_manual.h | 14 +++++++++++--
5 files changed, 30 insertions(+), 27 deletions(-)
diff --git a/configure b/configure
index 820b92c642..5d85213a87 100755
--- a/configure
+++ b/configure
@@ -16238,7 +16238,8 @@ fi
-for ac_func in cbrt dlopen fcvt fdatasync getpeereid getpeerucred getrlimit memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
+
+for ac_func in cbrt dlopen fcvt fdatasync getpeereid getpeerucred getrlimit memmove poll posix_fadvise pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs
do
as_ac_var=`echo "ac_cv_func_$ac_func" | $as_tr_sh`
{ echo "$as_me:$LINENO: checking for $ac_func" >&5
diff --git a/configure.in b/configure.in
index 52a8db226c..38c26f2194 100644
--- a/configure.in
+++ b/configure.in
@@ -1,5 +1,5 @@
dnl Process this file with autoconf to produce a configure script.
-dnl $PostgreSQL: pgsql/configure.in,v 1.584 2009/01/07 10:38:44 petere Exp $
+dnl $PostgreSQL: pgsql/configure.in,v 1.585 2009/01/11 18:02:17 tgl Exp $
dnl
dnl Developers, please strive to achieve this order:
dnl
@@ -1137,7 +1137,7 @@ PGAC_VAR_INT_TIMEZONE
AC_FUNC_ACCEPT_ARGTYPES
PGAC_FUNC_GETTIMEOFDAY_1ARG
-AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getpeereid getpeerucred getrlimit memmove poll pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
+AC_CHECK_FUNCS([cbrt dlopen fcvt fdatasync getpeereid getpeerucred getrlimit memmove poll posix_fadvise pstat readlink setproctitle setsid sigprocmask symlink sysconf towlower utime utimes waitpid wcstombs])
AC_CHECK_DECLS(fdatasync, [], [], [#include <unistd.h>])
AC_CHECK_DECLS(posix_fadvise, [], [], [#include <fcntl.h>])
diff --git a/src/backend/access/transam/xlog.c b/src/backend/access/transam/xlog.c
index daea9fafdf..9a2b3308b1 100644
--- a/src/backend/access/transam/xlog.c
+++ b/src/backend/access/transam/xlog.c
@@ -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().
- */
-#if defined(HAVE_DECL_POSIX_FADVISE) && defined(POSIX_FADV_DONTNEED)
- if (!XLogArchivingActive())
- posix_fadvise(openLogFile, 0, 0, POSIX_FADV_DONTNEED);
+ * 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(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,
diff --git a/src/include/pg_config.h.in b/src/include/pg_config.h.in
index 308f2bb6a3..3cc7c7ce6a 100644
--- a/src/include/pg_config.h.in
+++ b/src/include/pg_config.h.in
@@ -336,6 +336,9 @@
/* Define to 1 if you have the <poll.h> header file. */
#undef HAVE_POLL_H
+/* Define to 1 if you have the `posix_fadvise' function. */
+#undef HAVE_POSIX_FADVISE
+
/* Define to 1 if you have the POSIX signal interface. */
#undef HAVE_POSIX_SIGNALS
diff --git a/src/include/pg_config_manual.h b/src/include/pg_config_manual.h
index 3c1c1c0b8e..ff9d6ce45d 100644
--- a/src/include/pg_config_manual.h
+++ b/src/include/pg_config_manual.h
@@ -6,7 +6,7 @@
* for developers. If you edit any of these, be sure to do a *full*
* rebuild (and an initdb if noted).
*
- * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.35 2008/07/12 02:28:43 tgl Exp $
+ * $PostgreSQL: pgsql/src/include/pg_config_manual.h,v 1.36 2009/01/11 18:02:17 tgl Exp $
*------------------------------------------------------------------------
*/
@@ -112,7 +112,7 @@
#define ALIGNOF_BUFFER 32
/*
- * Disable UNIX sockets for those operating system.
+ * Disable UNIX sockets for certain operating systems.
*/
#if defined(WIN32)
#undef HAVE_UNIX_SOCKETS
@@ -125,6 +125,16 @@
#define HAVE_WORKING_LINK 1
#endif
+/*
+ * USE_POSIX_FADVISE controls whether Postgres will attempt to use the
+ * posix_fadvise() kernel call. Usually the automatic configure tests are
+ * sufficient, but some older Linux distributions had broken versions of
+ * posix_fadvise(). If necessary you can remove the #define here.
+ */
+#if HAVE_DECL_POSIX_FADVISE && defined(HAVE_POSIX_FADVISE)
+#define USE_POSIX_FADVISE
+#endif
+
/*
* This is the default directory in which AF_UNIX socket files are
* placed. Caution: changing this risks breaking your existing client
--
2.49.0