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Re: High context switches occurring

From: Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>
To: Vivek Khera <vivek(at)khera(dot)org>
Cc: Postgresql Performance <pgsql-performance(at)postgresql(dot)org>, "Anjan Dave" <adave(at)vantage(dot)com>
Subject: Re: High context switches occurring
Date: 2005-11-22 17:35:49
Message-ID: 12638.1132680949@sss.pgh.pa.us (view raw or flat)
Thread:
Lists: pgsql-performance
Vivek Khera <vivek(at)khera(dot)org> writes:
> On Nov 22, 2005, at 11:59 AM, Anjan Dave wrote:
>> This is a Dell Quad XEON. Hyperthreading is turned on, and I am  
>> planning to turn it off as soon as I get a chance to bring it down.

> You should probably also upgrade to Pg 8.0 or newer since it is a  
> known problem with XEON processors and older postgres versions.   
> Upgrading Pg may solve your problem or it may not.

PG 8.1 is the first release that has a reasonable probability of
avoiding heavy contention for the buffer manager lock when there
are multiple CPUs.  If you're going to update to try to fix this,
you need to go straight to 8.1.

I've recently been chasing a report from Rob Creager that seems to
indicate contention on SubTransControlLock, so the slru code is
likely to be our next bottleneck to fix :-(

			regards, tom lane

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