From: Daniel Andersen <anddan@linux-user.net>
To: Dan Maas <dmaas@maasdigital.com>
Cc: linux-kernel@vger.kernel.org
Subject: Re: Distinguish real vs. virtual CPUs?
Date: Tue, 22 Mar 2005 03:01:01 +0100 [thread overview]
Message-ID: <423F7C5D.4000203@linux-user.net> (raw)
In-Reply-To: <20050321202726.A7630@morpheus>
Dan Maas wrote:
> Is there a canonical way for user-space software to determine how many
> real CPUs are present in a system (as opposed to HyperThreaded or
> otherwise virtual CPUs)?
>
> We have an application that for performance reasons wants to run one
> process per CPU. However, on a HyperThreaded system /proc/cpuinfo
> lists two CPUs, and running two processes in this case is the wrong
> thing to do. (Hyperthreading ends up degrading our performance,
> perhaps due to cache or bus contention).
>
> Please CC replies.
>
> Thanks,
> Dan Maas
> -
The simplest thing to do would be to boot with the "noht" parameter.
Or you can use "schedtool" (google or freshmeat) to set the CPU-affinity
at runtime to avoid HyperThreading the processes.
Daniel Andersen
--
next prev parent reply other threads:[~2005-03-22 2:44 UTC|newest]
Thread overview: 11+ messages / expand[flat|nested] mbox.gz Atom feed top
2005-03-22 1:27 Distinguish real vs. virtual CPUs? Dan Maas
2005-03-22 1:56 ` Dave Jones
2005-03-22 11:55 ` Dr. David Alan Gilbert
2005-03-22 15:02 ` not for amd " Tom Vier
2005-03-22 2:01 ` Daniel Andersen [this message]
2005-03-22 2:12 ` J.A. Magallon
-- strict thread matches above, loose matches on Subject: below --
2005-03-22 4:29 Pallipadi, Venkatesh
2005-03-22 21:26 ` Bill Davidsen
2005-03-22 21:38 ` Jan Engelhardt
2005-03-23 17:52 ` Tom Vier
2005-03-23 21:32 ` Bill Davidsen
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