On Sun, Jan 16, 2011 at 7:13 PM, Greg Smith <g...@2ndquadrant.com> wrote: > I have finished a first run of benchmarking the current 9.1 code at various > sizes. See http://www.2ndquadrant.us/pgbench-results/index.htm for many > details. The interesting stuff is in Test Set 3, near the bottom. That's > the first one that includes buffer_backend_fsync data. This iall on ext3 so > far, but is using a newer 2.6.32 kernel, the one from Ubuntu 10.04. > > The results are classic Linux in 2010: latency pauses from checkpoint sync > will easily leave the system at a dead halt for a minute, with the worst one > observed this time dropping still for 108 seconds. That one is weird, but > these two are completely averge cases: > > http://www.2ndquadrant.us/pgbench-results/210/index.html > http://www.2ndquadrant.us/pgbench-results/215/index.html > > I think a helpful next step here would be to put Robert's fsync compaction > patch into here and see if that helps. There are enough backend syncs > showing up in the difficult workloads (scale>=1000, clients >=32) that its > impact should be obvious.
Have you ever tested Robert's other idea of having a metronome process do a periodic fsync on a dummy file which is located on the same ext3fs as the table files? I think that that would be interesting to see. Cheers, Jeff -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
