> From: Peter Geoghegan [mailto:pe...@2ndquadrant.com] > Sent: Wednesday, August 01, 2012 8:49 PM
On 1 August 2012 15:14, Amit Kapila <amit.kap...@huawei.com> wrote: >> I shall look into this aspect also(setting commit_delay based on raw sync). >> You also suggest if you want to run the test with different configuration. > Well, I was specifically interested in testing if half of raw sync > time was a widely useful setting, across a variety of different, > though representative I/O subsystems. Unfortunately, without some > context about raw sync speed to go along with your numbers, I cannot > advance or disprove that idea. Raw sync speed data -------------------------- 2 seconds per test O_DIRECT supported on this platform for open_datasync and open_sync. Compare file sync methods using one 8kB write: (in wal_sync_method preference order, except fdatasync is Linux's default) open_datasync n/a fdatasync 165.506 ops/sec fsync 166.647 ops/sec fsync_writethrough n/a open_sync 164.654 ops/sec 165.506 * 8KB operations can perform in one sec. so 1 * 8KB operation takes 6.042 msec. > It would also have been nice to see a baseline number of 0 too, to get > an idea of how effective commit_delay may now be. However, that's > secondary. In the data sent yesterday commit_delay=0 was there. With Regards, Amit Kapila. -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers