Re: Performance!

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Claus Guttesen wrote:
I have read all related threads about performance problems with multi
core systems but still have no idea what to do to make thinks better.
Below are results of testing postgresql on HP DL380G5 using sysbench.
The results are comparable to:
http://blog.insidesystems.net/articles/2007/04/11/postgresql-scaling-on-6-2-and-7-0
but the same tests running on the same hardware using Linux (kernel
2.6.18-53.1.4.el5 SMP x86_64) are very different.
PostgreSQL is tuned equal.

results:
FreeBSD 7.0-BETA4 amd64 (cvsup on 20.12) GENERIC with SCHED_ULE
#threads #transactions/sec user/system
1 500 7.4%,5.3%
5 1990 30.9%,23.4%
10 2510 39.9%,35.0%
20 2549 44.5%,43.5%
40 1921 29.8%,59.4%
60 1580 22.7%,70.6%
80 1341 18.9%,75.9%
100 1227 16.5%,79.3%

Linux
#threads #transactions/sec
1 693
5 3539
10 5789
20 5791
40 5661
60 5517
80 5401
100 5319

What can be done to improve these results?

What postgres-version did you use for this benchmark? Eventhough this
is a synthetic benchmark the difference in performance may indicate
some penalties on 8-core servers on FreeBSD.

8.2.5 from ports


According to http://people.freebsd.org/~kris/scaling/mysql.html mysql
scale the same until until 8 clients on both Linux and FreeBSD. This
is an older test though and Linux has probably done some
optimizations.

Could be interesting so see whether the results differ if you disable
one of the cpu's and rerun the tests.



2 cores:
#threads #transactions/sec user/system
1 541 27.8%,19.0%
5 1068 57.1%,28.4%
40 1086 55.2%,32.1%
100 997 57.5%,28.9%

4 cores:
#threads #transactions/sec user/system
1 512 12.3%,8.8%
5 1531 50.3%,31.5%
10 1651 51.6%,33.7%
40 1490 47.3%,37.8%
60 1320 44.0%,44.8%
100 1117 37.5%,51.8%




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