Re: Wierd context-switching issue on Xeon

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(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 00:57:53
Message-ID: 20040428185753.56614b2c@thunder.mshome.net
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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

--
18:55:22 up 1:40, 4 users, load average: 2.00, 2.04, 2.00
Linux 2.6.5-01 #7 SMP Fri Apr 16 22:45:31 MDT 2004

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