Performance!

[Krassimir Slavchev]

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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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