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SubjectRE: more dbt-2 results hyperthreading on linux-2.6.0-test11
Date
From
I'm not familiar with this particular workload, but noticed higher idle
and wait time with HT enabled, compared to HT-disabled case. This kind
of symptom often indicated insufficient I/O bandwidth from my
experience, and faster systems (with more threads) tend to show lower
throughput because you end up measuring disk seek time of more I/O
requests. Can you add more disk controller(s) and disks?

Jun
> -----Original Message-----
> From: linux-kernel-owner@vger.kernel.org [mailto:linux-kernel-
> owner@vger.kernel.org] On Behalf Of markw@osdl.org
> Sent: Friday, December 12, 2003 2:28 PM
> To: piggin@cyberone.com.au
> Cc: mingo@redhat.com; linux-kernel@vger.kernel.org; pgsql-
> hackers@postgresql.org
> Subject: more dbt-2 results hyperthreading on linux-2.6.0-test11
>
> Hi Nick,
>
> Here are the results of the comparisons I said I would do.
>
> no-hyperthreading:
> http://developer.osdl.org/markw/dbt2-pgsql/282/
> - metric 2288.43
> - baseline
>
> hyperthreading:
> http://developer.osdl.org/markw/dbt2-pgsql/278/
> - metric 1944.42
> - 15% throughput decrease
>
> hyperthreading w/ Ingo's C1 patch:
> http://developer.osdl.org/markw/dbt2-pgsql/277/
> - metric 1978.39
> - 13.5% throughput decrease
>
> hyperthreading w/ Nick's w26 patch:
> http://developer.osdl.org/markw/dbt2-pgsql/274/
> - metric 1955.91
> - 14.5% throughput decrease
>
> It looks like there is some marginal benefit to your or Ingo's patches
> with a workload like DBT-2. I probably don't understand enough about
> hyperthreading, but I wonder if there's something PostgreSQL can do to
> take advantage of hyperthreading
>
> Anyway, each link has pointers to readprofile and annotated oprofile
> assembly output (if you find that useful.) I haven't done enough
tests
> to have an idea of the error margin, but I wouldn't be surprised if
it's
> at least 1%.
>
> Let me know if there's anything else you'd like me to try.
>
> Thanks,
> Mark
> -
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