RE: scheduling co-processors

From: Sherif F. Fahmy
Date: Tue Aug 04 2009 - 06:28:28 EST


> -----Original Message-----
> From: linux-kernel-owner@xxxxxxxxxxxxxxx [mailto:linux-kernel-
> owner@xxxxxxxxxxxxxxx] On Behalf Of Casey Dahlin
> Sent: Monday, August 03, 2009 11:28 PM
> To: Sherif Fadel
> Cc: linux-kernel@xxxxxxxxxxxxxxx
> Subject: Re: scheduling co-processors
>
> On 08/03/2009 11:08 AM, Sherif Fadel wrote:
> > Hi,
> >
> > I have a dual-core system on which I would like to treat one
> processor
> > as a scheduling co-processor. I have already implemented some custom
> > scheduling policies and tested them with SMP disabled, I would not
> like
> > to see if it is possible to have the scheduling algorithm running on
> one
> > core and the scheduled tasks running on another.
> >
> > I do not know if I can somehow use cpus_allowed to restrict the
> kernel
> > to one core and the running tasks to another. Is this possible? If
> so,
> > could you please inform me how one would go about this?
> >
> > In case you are wondering why I would need this, I am writing a bunch
> of
> > high-overhead distributed scheduling algorithms and I want to
> mitigate
> > their overhead in this way.
> >
> > Thanks.
> >
>
> The design I would have for this would be to have a kthread that does
> whatever busy work your scheduler has as a separate process. You could
> then replace the existing scheduler with a sort of "schedulerlet" that
> would simply schedule according to directions queued up for it by the
> kthread task. From there cpu affinity should get you the "dedicated
> scheduler processor" you want.
>
> I can't even begin to envision the scheduling algorithm that would be
> able to operate this way, but I have to assume that if it makes sense
> for your scheduler to run on another CPU then it must be able to fit
> into this pattern.

Thanks for the info. I think that this will do perfectly.

>
> --CJD
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