On Sat, Mar 10, 2012 at 7:55 PM, Robert Haas <robertmh...@gmail.com> wrote: > I've finally been able to run some more tests of the effect of > adjusting wal_buffers to values higher than 16MB. I ran the test on > the 16 core (x 4 hw threads/core) IBM POWER7 machine, with my usual > configuration settings: > > shared_buffers = 8GB > maintenance_work_mem = 1GB > synchronous_commit = off > checkpoint_segments = 300 > checkpoint_timeout = 15min > checkpoint_completion_target = 0.9 > wal_writer_delay = 20ms > > I ran three 30-minute tests at scale factor 300 with wal_buffers set > at various values from 16MB up to 160MB, in multiples of 16MB, using > pgbench with 32 clients and 32 threads in each case. The short > version is that 32MB seems to be significantly better than 16MB, by > about 1000 tps, and after that it gets murky; full results are below.
On Nate Boley's machine, the difference was ~100% increase rather than ~10%. Do you think the difference is in the CPU architecture, or the IO subsystem? Also, do you have the latency numbers? 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
