Re: SMP question

Zwane Mwaikambo (zwane@linuxpower.ca)
Wed, 11 Jun 2003 17:25:40 -0400 (EDT)


On Wed, 11 Jun 2003, Artemio wrote:

> 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.

Sounds like an RTLinux bug, perhaps you should elaborate on that on the
RTLinux mailing list.

> 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?

Depending on your load it could make a very significant difference.

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

If you have that option you didn't need hard realtime in the first place.

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

HT w/ SMP = You'll have to do your own tests with your applications
HT w/o SMP = Normal UP

Zwane

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