RE: more dbt-2 results hyperthreading on linux-2.6.0-test11

[Nakajima, Jun]

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@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of markw@xxxxxxxx
> Sent: Friday, December 12, 2003 2:28 PM
> To: piggin@xxxxxxxxxxxxxxx
> Cc: mingo@xxxxxxxxxx; linux-kernel@xxxxxxxxxxxxxxx; pgsql-
> hackers@xxxxxxxxxxxxxx
> 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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