RE: SMP question

From: David Schwartz (
Date: Wed Jun 11 2003 - 15:14:53 EST

> 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.


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This archive was generated by hypermail 2b29 : Sun Jun 15 2003 - 22:00:29 EST