> From: pgsql-hackers-ow...@postgresql.org [mailto:pgsql-hackers-ow...@postgresql.org] On Behalf Of Peter Geoghegan > Sent: Sunday, July 29, 2012 9:09 PM
> I made what may turn out to be a useful observation during the > development of the patch, which was that for both the tpc-b.sql and > insert.sql pgbench-tools scripts, a commit_delay of half of my > wal_sync_method's reported raw sync speed looked optimal. I use Linux, > so my wal_sync_method happened to have been fdatasync. I measured this > using pg_test_fsync. I have done some basic test for commit_delay parameter OS version: suse linux 10.3 postgresql version: 9.3 dev on x86-64, compiled by gcc (GCC) 4.1.2 20070115 Machine details: 8 core cpu, 24GB RAM. Testcase: pgbench tcp_b test. Before running the benchmark suite, the buffers are loaded by using pg_prewarm utility. Test Results are attached with this mail. Run1,Run2,Run3 means the same test has ran 3 times. > It would be useful, for a start, if I had numbers for a battery-backed > write cache. I don't have access to one right now though, nor do I > have access to any more interesting hardware, which is one reason why > I'm asking for help with this. > I like to run "sync" prior to running pg_test_fsync, just in case. > [peter@peterlaptop pg_test_fsync]$ sync >I then interpret the following output: > [peter@peterlaptop pg_test_fsync]$ pg_test_fsync > 2 seconds per test > O_DIRECT supported on this platform for open_datasync and open_sync. > Compare file sync methods using one 8kB write: > (in wal_sync_method preference order, except fdatasync > is Linux's default) > open_datasync 112.940 ops/sec > fdatasync 114.035 ops/sec > fsync 21.291 ops/sec > *** SNIP *** I shall look into this aspect also(setting commit_delay based on raw sync). You also suggest if you want to run the test with different configuration. With Regards, Amit Kapila.
| Machine details | ||||||||
| CPU | 8 core | RAM | 24GB | |||||
| OS | suse linux 10.3 | |||||||
| Server Configuration | ||||||||
| sync commit | on | shared buffers | 1GB | |||||
| Pgbench tcp_b benchmark suite | ||||||||
| threads | 8 | clients | 16 | |||||
| scale | 75 | fill factor | 100 | |||||
| pgbench | delay = 0 | delay = 3000 | delay = 4000 | delay = 5000 | ||||
| TPS | Total ops | TPS | Total ops | TPS | Total ops | TPS | Total ops | |
| Run1 | 968 | 583060 | 973 | 584130 | 935 | 561516 | 916 | 550043 |
| Run2 | 971 | 583035 | 963 | 578560 | 971 | 585143 | 921 | 556471 |
| Run3 | 995 | 597368 | 978 | 590085 | 998 | 599371 | 872 | 523890 |
| Avg | 978 | 587821 | 971.33333 | 584258.3 | 968 | 582010 | 903 | 543468 |
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