From: Dirk Lutzebäck <lutzeb@aeccom.com>
To: Jeffrey W. Baker <jwbaker@acm.org>
Cc: josh@agliodbs.com, pgsql-performance@postgresql.org, Sven Geisler <sgeisler@aeccom.com>
Subject: Re: Performance problems on 4/8way Opteron (dualcore) HP
Date: Sun, 31 Jul 2005 12:11:02 +0200
Message-ID: <42ECA3B6.3000607@aeccom.com> (raw)
In-Reply-To: <1122663342.6814.5.camel@toonses.gghcwest.com>
References: <42EA5D18.9020204@aeccom.com>
<200507291046.10318.josh@agliodbs.com>
<1122663342.6814.5.camel@toonses.gghcwest.com>
Hi Jeff,
which box are you running precisely and which OS/kernel?
We need to run 32bit because we need failover to 32 bit XEON system
(DL580). If this does not work out we probably need to switch to 64 bit
(dump/restore) and run a nother 64bit failover box too.
Regards,
Dirk
Jeffrey W. Baker wrote:
> On Fri, 2005-07-29 at 10:46 -0700, Josh Berkus wrote:
>
>>Dirk,
>>
>>
>>>does anybody have expierence with this machine (4x 875 dual core Opteron
>>>CPUs)?
>
>
> I'm using dual 275s without problems.
>
>
>>Nope. I suspect that you may be the first person to report in on
>>dual-cores. There may be special compile issues with dual-cores that
>>we've not yet encountered.
>
>
> Doubtful. However you could see improvements using recent Linux kernel
> code. There have been some patches for optimizing scheduling and memory
> allocations.
>
> However, if you are running this machine in 32-bit mode, why did you
> bother paying $14,000 for your CPUs? You will get FAR better
> performance in 64-bit mode. 64-bit mode will give you 30-50% better
> performance on PostgreSQL loads, in my experience. Also, if I remember
> correctly, the 32-bit x86 kernel doesn't understand Opteron NUMA
> topology, so you may be seeing poor memory allocation decisions.
>
> -jwb
>
>
>>>We run RHEL 3.0, 32bit and under high load it is a drag. We
>>>mostly run memory demanding queries. Context switches are pretty much
>>>around 20.000 on the average, no cs spikes when we run many processes in
>>>parallel. Actually we only see two processes in running state! When
>>>there are only a few processes running context switches go much higher.
>>>At the moment we are much slower that with a 4way XEON box (DL580).
>>
>>Um, that was a bit incoherent. Are you seeing a CS storm or aren't you?
>>
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To: pgsql-performance@postgresql.org
Cc: lutzeb@aeccom.com, jwbaker@acm.org, sgeisler@aeccom.com
Subject: Re: Performance problems on 4/8way Opteron (dualcore) HP
In-Reply-To: <42ECA3B6.3000607@aeccom.com>
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