From: Con Kolivas <kernel@kolivas.org>
To: Nick Piggin <piggin@cyberone.com.au>
Subject: Re: 2.6.0-test2-mm3 osdl-aim-7 regression
Date: Thu, 7 Aug 2003 20:01:13 +1000
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On Thu, 7 Aug 2003 18:25, Nick Piggin wrote:
> >The more frequently you round robin the lower the scheduler latency
> > between SCHED_OTHER tasks of the same priority. However, the longer the
> > timeslice the more benefit you get from cpu cache. Where is the sweet
> > spot? Depends on the hardware and your usage requirements of course, but
> > Ingo has empirically chosen 25ms after 50ms seemed too long. Basically
> > cache trashing becomes a real problem with timeslices below ~7ms on
> > modern hardware in my limited testing. A minor quirk in Ingo's original
> > code means _occasionally_ a task will be requeued with <3ms to go. It
> > will be interesting to see if fixing this (which O12.2+ does) makes a big
> > difference or whether we need to reconsider how frequently (if at all) we
> > round robin tasks.
>
> Why not have it dynamic? CPU hogs get longer timeslices (but of course
> can be preempted by higher priorities).

Funny you should say that. Before Ingo merged his A3 changes, that's what my 
version of them did.

Con

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