Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries - Mailing list pgsql-performance

From Gunnar \"Nick\" Bluth
Subject Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries
Date
Msg-id 50954FAF.3060905@pro-open.de
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In response to Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries  (Petr Praus <petr@praus.net>)
Responses Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries  (Petr Praus <petr@praus.net>)
Re: Re: Increasing work_mem and shared_buffers on Postgres 9.2 significantly slows down queries  (Jeff Janes <jeff.janes@gmail.com>)
List pgsql-performance
Am 03.11.2012 16:20, schrieb Petr Praus:

Your CPUs are indeed pretty oldschool. FSB based, IIRC, not NUMA. A process migration would be even more expensive there.


Ok, I've actually looked these up now... at the time these were current, I was in the lucky situation to only deal with Opterons. And actually, with these CPUs it is pretty possible that Scott Marlowe's hint (check vm.zone_reclaim_mode) was pointing in the right direction. Did you check that?


Yes, same behaviour. I let the shared_buffers be the default (which is 8MB). With work_mem 1MB the query runs fast, with 96MB it runs slow (same times as before). It really seems that the culprit is work_mem.


Well, I'm pretty sure that having more work_mem is a good thing (tm) normally ;-)
-- 
Gunnar "Nick" Bluth
RHCE/SCLA

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Email: gunnar.bluth@pro-open.de
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