On Thu, Mar 24, 2016 at 8:08 AM, Amit Kapila <amit.kapil...@gmail.com> wrote: > > On Thu, Mar 24, 2016 at 5:40 AM, Andres Freund <and...@anarazel.de> wrote: > > > > Even after changing to scale 500, the performance benefits on this, > > older 2 socket, machine were minor; even though contention on the > > ClogControlLock was the second most severe (after ProcArrayLock). > > > > I have tried this patch on mainly 8 socket machine with 300 & 1000 scale factor. I am hoping that you have tried this test on unlogged tables and by the way at what client count, you have seen these results. > > > Afaics that squares with Jesper's result, which basically also didn't > > show a difference either way? > > > > One difference was that I think Jesper has done testing with synchronous_commit mode as off whereas my tests were with synchronous commit mode on. >
On again looking at results posted by Jesper [1] and Mithun [2], I have one more observation which is that in HEAD, the performance doesn't dip even at higher client count (>75) on tests done by Jesper, whereas the results of tests done by Mithun indicate that it dips at high client count (>64) in HEAD and that is where the patch is helping. Now there is certainly some difference in test environment like Jesper has done testing on 2 socket m/c whereas mine and Mithun's tests were done 4 or 8 socket m/c. So I think the difference in TPS due to reduced contention on CLogControlLock are mainly visible with high socket m/c. Can anybody having access to 4 or more socket m/c help in testing this patch with --unlogged-tables? [1] - http://www.postgresql.org/message-id/56e9a596.2000...@redhat.com [2] - http://www.postgresql.org/message-id/cad__oujrdwqdjdovhahqldg-6ivu6ibci9ij1qpu6atuqpl...@mail.gmail.com With Regards, Amit Kapila. EnterpriseDB: http://www.enterprisedb.com
