Horton

Re: Wierd context-switching issue on Xeon

Bruce Momjian <pgman@candle.pha.pa.us>

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From: Bruce Momjian <pgman@candle.pha.pa.us>
To: pg@fastcrypt.com
Cc: Robert Creager <Robert_Creager@LogicalChaos.org>, Josh Berkus <josh@agliodbs.com>, Dirk_Lutzebäck <lutzeb@aeccom.com>, ohp@pyrenet.fr, Tom Lane <tgl@sss.pgh.pa.us>, Joe Conway <mail@joeconway.com>, "scott.marlowe" <scott.marlowe@ihs.com>, pgsql-performance@postgresql.org, Neil Conway <neilc@samurai.com>
Date: 2004-05-20T01:20:20Z
Lists: pgsql-performance 
Did we ever come to a conclusion about excessive SMP context switching
under load?

---------------------------------------------------------------------------

Dave Cramer wrote:
> Robert,
> 
> The real question is does it help under real life circumstances ? 
> 
> Did you do the tests with Tom's sql code that is designed to create high
> context switchs ?
> 
> Dave
> On Sun, 2004-05-02 at 11:20, Robert Creager wrote:
> > Found some co-workers at work yesterday to load up my library...
> > 
> > The sample period is 5 minutes long (vs 2 minutes previously):
> > 
> > Context switches -          avg    max
> > 
> > Default 7.4.1 code :       48784 107354
> > Default patch - 10 :       20400  28160
> > patch at 100       :       38574  85372
> > patch at 1000      :       41188 106569
> > 
> > The reading at 1000 was not produced under the same circumstances as the prior
> > readings as I had to replace my device under test with a simulated one.  The
> > real one died.
> > 
> > The previous run with smaller database and 120 second averages:
> > 
> > Context switches -          avg    max
> > 
> > Default 7.4.1 code :       10665  69470
> > Default patch - 10 :       17297  21929
> > patch at 100       :       26825  87073
> > patch at 1000      :       37580 110849
> -- 
> Dave Cramer
> 519 939 0336
> ICQ # 14675561
> 
> 
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