Performance!

Claus Guttesen kometen at gmail.com
Thu Dec 20 06:35:54 PST 2007


> 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.

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.

-- 
regards
Claus

When lenity and cruelty play for a kingdom,
the gentlest gamester is the soonest winner.

Shakespeare


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