Re: [PATCH] O13int for interactivity

From: Mike Galbraith (efault@gmx.de)
Date: Tue Aug 05 2003 - 04:09:02 EST


At 06:43 PM 8/5/2003 +1000, Con Kolivas wrote:
>On Tue, 5 Aug 2003 18:27, Mike Galbraith wrote:
> > At 06:20 PM 8/5/2003 +1000, Con Kolivas wrote:
> > >Every experiment I've tried at putting tasks at the start of the queue
> > >instead
> > >of the end has resulted in some form of starvation so should not be
> > > possible for any user task and I've abandoned it.
> >
> > (ditto:)
>
>Superuser access real time tasks may be worth reconsidering though...

If they were guaranteed ultra-light, maybe, but userland is just not
trustworthy.

Better imho would be something like Davide's SOFT_RR with an additional
automatic priority adjust per cpu usage or something (cpu usage being a
[very] little bit of a latency hint, and a great 'hurt me' hint). Best
would be an API that allowed userland applications to describe their
latency requirements explicitly, with the scheduler watching users of this
API like a hawk, ever ready to sanction abusers. Anything I think about in
this area gets uncomfortably close to hard rt though, and all of the wisdom
I've heard on LKLM over the years wrt separation of problem spaces comes
flooding back.

         -Mike

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