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From: Con Kolivas <kernel@kolivas.org>
To: "Martin J. Bligh" <mbligh@aracnet.com>,
       linux-kernel <linux-kernel@vger.kernel.org>
Subject: Re: xmms (audio) skipping in 2.5 (not 2.4)
Date: Tue, 4 Mar 2003 19:15:43 +1100
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On Tue, 4 Mar 2003 06:48 pm, Martin J. Bligh wrote:
> >> >> So ... is there any easy way I can diagnose this? Does anyone else
> >> >> have a similar problem?
> >> >
> >> > Most of us who have worked with an O(1) scheduler based kernel have
> >> > found this  at various times. See the previous discussion with akpm
> >> > about the interactivity estimator. Akpm found that decreasing the
> >> > maximum timeslice duration would blunt the effect of the interactivity
> >> > estimator giving preference to the "wrong" task. In 2.4.20-ck4 I avoid
> >> > this problem with the  "desktop tuning" of making the max
> >> > timeslice==min timeslice. Try an -mm  kernel with the scheduler
> >> > tunables patch and try playing with the max  timeslice. Most have
> >> > found that <=25 will usually stop these skips. The  default max
> >> > timeslice of 300ms is just too long for the desktop and interactivity
> >> > estimator.
> >>
> >> Heh, cool. I have the same patch in my tree too, fixed it without
> >> rebooting even ;-) Still a *tiny* bit of skipping, but infinitely better
> >> than it was.
> >
> > Try decreasing prio_bonus_ratio to 15 as well
>
> Doesn't seem to make much difference, actually.
> But "waggle scrollbar a bit" isn't very scientific .. ;-)
> Does contest (or anything else) measure this kind of thing more precisely?

Last time I tried to do a whole swag of tunables it was showing differences 
but I was plagued by memory leaks ruining the data. I'll try again in the 
near future. Also Bill Davidsen's trivial response benchmark may show 
something too.

Con

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