On 7 August 2013 18:49, Jon Nelson <jnelson+pg...@jamponi.net> wrote: > On Wed, Aug 7, 2013 at 12:42 PM, Thom Brown <t...@linux.com> wrote: >> for i in 1 2 5 10 100; do ./test_fallocate foo $i 1; done >> method: classic. 1 open/close iterations, 1 rewrite in 0.6380s >> method: posix_fallocate. 1 open/close iterations, 1 rewrite in 0.3204s >> method: glibc emulation. 1 open/close iterations, 1 rewrite in 0.6274s >> method: classic. 2 open/close iterations, 1 rewrite in 1.2908s >> method: posix_fallocate. 2 open/close iterations, 1 rewrite in 0.6596s >> method: glibc emulation. 2 open/close iterations, 1 rewrite in 1.2666s >> method: classic. 5 open/close iterations, 1 rewrite in 3.1419s >> method: posix_fallocate. 5 open/close iterations, 1 rewrite in 1.5930s >> method: glibc emulation. 5 open/close iterations, 1 rewrite in 3.1516s >> method: classic. 10 open/close iterations, 1 rewrite in 6.2912s >> method: posix_fallocate. 10 open/close iterations, 1 rewrite in 3.2626s >> method: glibc emulation. 10 open/close iterations, 1 rewrite in 6.3667s >> method: classic. 100 open/close iterations, 1 rewrite in 67.4174s >> method: posix_fallocate. 100 open/close iterations, 1 rewrite in 37.8788s >> method: glibc emulation. 100 open/close iterations, 1 rewrite in 55.0714s > > OK. That's interesting, and a good data point. > > One thing you could try manually disabling the use of posix_fallocate in > 269e78. > After running ./configure --stuff-here > edit src/include/pg_config.h and comment out the following line (on or > around line 374) > #define HAVE_POSIX_FALLOCATE 1 > > *then* build postgresql and see if the performance hit is still there.
Okay, done that. The TPS increases again: 2308.807568 / 2554.264572 / 2563.190204 And I did run ./configure... before removing the line, and built it after the change. -- Thom -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
