Tom Lane wrote:
Just eyeing the code ... another thing we changed since 8.3 is to enable
posix_fadvise() calls for WAL. Any of the complaints want to try diking
out this bit of code (near line 2580 in src/backend/access/transam/xlog.c)?
#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
ok after a bit of bisecting I'm happy to announce the winner of the contest:
http://archives.postgresql.org/pgsql-committers/2008-11/msg00054.php
this patch causes a 25-30% performance regression for WAL logged copy,
however in the WAL bypass case (maybe that was what got tested?) it
results in a 20% performance increase.
the raw numbers using the upthread posted minimal postgresql.conf are:
post patch/wal logged: 4min10s/4min19/4min12
post patch/wal bypass: 1m55s/1m58s/2m00
prepatch/wal logged: 2m55s/3min00/2m59
prepatch/wal bypass: 2m22s/2m18s/2m20s
Stefan
--
Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org)
To make changes to your subscription:
http://www.postgresql.org/mailpref/pgsql-hackers
