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Subject: Re: [patch][rfc] quell interactive feeding frenzy
From: Mike Galbraith <efault@gmx.de>
To: Con Kolivas <kernel@kolivas.org>
Cc: bert hubert <bert.hubert@netherlabs.nl>,
       lkml <linux-kernel@vger.kernel.org>, Ingo Molnar <mingo@elte.hu>,
       Andrew Morton <akpm@osdl.org>, Nick Piggin <nickpiggin@yahoo.com.au>,
       Peter Williams <pwil3058@bigpond.net.au>
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Date: Thu, 13 Apr 2006 13:05:24 +0200
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On Thu, 2006-04-13 at 20:16 +1000, Con Kolivas wrote:
> On Thursday 13 April 2006 17:41, Mike Galbraith wrote:
> > This way also allowed me to eliminate the interactive agony of an array
> > switch when at 100% cpu.  Seems to work well.  No more agony, only tiny
> > pin pricks.
> >
> 
> Comments.
> 
> > +repeat:
> > +	while ((idx = find_next_bit(bitmap, MAX_PRIO, idx)) < MAX_PRIO) {
> 
> ...
> 
> > +		goto repeat;
> 
> ...
> 
> > +               if (rq->nr_running > 1)
> > +                       requeue_starving(rq, now);
> 
> An O(n) function in scheduler_tick is probably not the way to tackle this.

Why not?  It's one quick-like-bunny stop per occupied queue per slice
completion.

	-Mike