Re: Wierd context-switching issue on Xeon

From: ohp(at)pyrenet(dot)fr
To: Robert Creager <Robert_Creager(at)LogicalChaos(dot)org>
Cc: Josh Berkus <josh(at)agliodbs(dot)com>, pg(at)fastcrypt(dot)com, Dirk_Lutzebäck <lutzeb(at)aeccom(dot)com>, Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Joe Conway <mail(at)joeconway(dot)com>, "scott(dot)marlowe" <scott(dot)marlowe(at)ihs(dot)com>, Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org, Neil Conway <neilc(at)samurai(dot)com>
Subject: Re: Wierd context-switching issue on Xeon
Date: 2004-04-29 13:20:18
Message-ID: Pine.UW2.4.53.0404291519190.7358@server.pyrenet.fr
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Hi

I'd LOVE to contribute on this but I don't have vmstat and I'm not running
linux.

How can I help?
Regards
On Wed, 28 Apr 2004, Robert Creager wrote:

> Date: Wed, 28 Apr 2004 18:57:53 -0600
> From: Robert Creager <Robert_Creager(at)LogicalChaos(dot)org>
> To: Josh Berkus <josh(at)agliodbs(dot)com>
> Cc: pg(at)fastcrypt(dot)com, Dirk_Lutzebäck <lutzeb(at)aeccom(dot)com>, ohp(at)pyrenet(dot)fr,
> Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us>, Joe Conway <mail(at)joeconway(dot)com>,
> scott.marlowe <scott(dot)marlowe(at)ihs(dot)com>,
> Bruce Momjian <pgman(at)candle(dot)pha(dot)pa(dot)us>, pgsql-performance(at)postgresql(dot)org,
> Neil Conway <neilc(at)samurai(dot)com>
> Subject: Re: [PERFORM] Wierd context-switching issue on Xeon
>
> When grilled further on (Wed, 21 Apr 2004 10:29:43 -0700),
> Josh Berkus <josh(at)agliodbs(dot)com> confessed:
>
> > Dave,
> >
> > > After some testing if you use the current head code for s_lock.c which
> > > has some mods in it to alleviate this situation, and change
> > > SPINS_PER_DELAY to 10 you can drastically reduce the cs with tom's test.
> > > I am seeing a slight degradation in throughput using pgbench -c 10 -t
> > > 1000 but it might be liveable, considering the alternative is unbearable
> > > in some situations.
> > >
> > > Can anyone else replicate my results?
> >
> > Can you produce a patch against 7.4.1? I'd like to test your fix against a
> > real-world database.
>
> I would like to see the same, as I have a system that exhibits the same behavior
> on a production db that's running 7.4.1.
>
> Cheers,
> Rob
>
>
>

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