On Wed, Mar 14, 2012 at 7:20 AM, Robert Haas <robertmh...@gmail.com> wrote: > On Tue, Mar 13, 2012 at 3:48 PM, Robert Haas <robertmh...@gmail.com> wrote: >> On Mon, Mar 12, 2012 at 4:45 PM, Jeff Janes <jeff.ja...@gmail.com> wrote: >>> Rerunning all 4 benchmarks (both 16MB and 32MB wal_buffers on both >>> machines) with fsync=off (as well as synchronous_commit=off still) >>> might help clarify things. >> >> I reran the 32-client benchmark on the IBM machine with fsync=off and got >> this: >> >> 32MB: tps = 26809.442903 (including connections establishing) >> 16MB: tps = 26651.320145 (including connections establishing) >> >> That's a speedup of nearly a factor of two, so clearly fsync-related >> stalls are a big problem here, even with wal_buffers cranked up >> through the ceiling. > > And here's a tps plot with wal_buffers = 16MB, fsync = off. The > performance still bounces up and down, so there's obviously some other > factor contributing to latency spikes
Initialization of WAL file? Do the latency spikes disappear if you start benchmark after you prepare lots of the recycled WAL files? Regards, -- Fujii Masao NIPPON TELEGRAPH AND TELEPHONE CORPORATION NTT Open Source Software Center -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers
