From: "David Schwartz" <davids@webmaster.com>
To: "Artemio" <artemio@artemio.net>,
       "Linux Kernel Mailing List" <linux-kernel@vger.kernel.org>
Subject: RE: SMP question
Date: Wed, 11 Jun 2003 13:14:53 -0700
Message-ID: <MDEHLPKNGKAHNMBLJOLKMEJLDJAA.davids@webmaster.com>
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> I'm building a hard real-time Linux (RTLinux) system on a 2x Xeon
> machine. If
> I compile and run a 2.4.18 kernel with SMP support, rtlinux hangs the
> machine. However, with SMP disabled, rtlinux and all it's hard-realtime
> applications runs okay.

> So, I have to deside between these two:

>  - Run rtlinux and hard-realtime applications on a kernel without
> SMP support.
> How much performance will I loose this way? Is SMP *THAT* critical?

	You will lose about half your CPU power.

>  - Run all tasks in a usual way, no hard realtime, but with SMP support.

> What would you suggest?

	If you don't install a kernel with SMP support, you might as well remove
one processor.

> Also, if I turn hyperthreading off, how will it influence the
> system with SMP
> support? Without SMP support?

	In a system with more than one physical CPU, hyperthreading is not that big
of a performance boost.

	DS


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