On 2014-02-03 17:51:20 -0800, Peter Geoghegan wrote: > On Sun, Feb 2, 2014 at 6:00 AM, Andres Freund <and...@2ndquadrant.com> wrote: > > On 2014-02-01 19:47:29 -0800, Peter Geoghegan wrote: > >> Here are the results of a benchmark on Nathan Boley's 64-core, 4 > >> socket server: > >> http://postgres-benchmarks.s3-website-us-east-1.amazonaws.com/amd-4-socket-rwlocks/ > > > > That's interesting. The maximum number of what you see here (~293125) > > is markedly lower than what I can get. > > > > ... poke around ... > > > > Hm, that's partially because you're using pgbench without -M prepared if > > I see that correctly. The bottleneck in that case is primarily memory > > allocation. But even after that I am getting higher > > numbers: ~342497. > > > > Trying to nail down the differnce it oddly seems to be your > > max_connections=80 vs my 100. The profile in both cases is markedly > > different, way much more spinlock contention with 80. All in > > Pin/UnpinBuffer(). > > I updated this benchmark, with your BufferDescriptors alignment patch > [1] applied on top of master (while still not using "-M prepared" in > order to keep the numbers comparable). So once again, that's: > > http://postgres-benchmarks.s3-website-us-east-1.amazonaws.com/amd-4-socket-rwlocks/ > > It made a bigger, fairly noticeable difference, but not so big a > difference as you describe here. Are you sure that you saw this kind > of difference with only 64 clients, as you mentioned elsewhere [1] > (perhaps you fat-fingered [1] -- "-cj" is ambiguous)? Obviously > max_connections is still 80 in the above. Should I have gone past 64 > clients to see the problem? The best numbers I see with the [1] patch > applied on master is only ~327809 for -S 10 64 clients. Perhaps I've > misunderstood.
That's likely -M prepared. It was with -c 64 -j 64... Greetings, Andres Freund -- Andres Freund http://www.2ndQuadrant.com/ PostgreSQL Development, 24x7 Support, Training & Services -- Sent via pgsql-hackers mailing list (pgsql-hackers@postgresql.org) To make changes to your subscription: http://www.postgresql.org/mailpref/pgsql-hackers