[Linux-ia64] Re: web page on O(1) scheduler

Mike Galbraith
2003-05-22T05:52:44Z

At 08:38 PM 5/21/2003 -0400, Rik van Riel wrote:
>On Wed, 21 May 2003, Mike Galbraith wrote:
> > At 11:49 PM 5/20/2003 -0700, David Mosberger wrote:
> > >Recently, I started to look into some odd performance behaviors of the
> > >O(1) scheduler. I decided to document what I found in a web page
> > >at:
> > >
> > > http://www.hpl.hp.com/research/linux/kernel/o1.php
> >
> > The page mentions persistent starvation. My own explorations of this
> > issue indicate that the primary source is always selecting the highest
> > priority queue.
>
>It's deeper than that. The O(1) scheduler doesn't consider
>actual CPU usage as a factor of CPU priority.

Oh, there's no doubt in my mind that it's _much_ deeper than my little
surface scratchings ;-)

It does consider cpu usage though. Your run history is right there in your
accumulated sleep_avg. Unfortunately (in some ways, fortunate in others..
conflict) that information can be diluted down to nothing instantly by new
input from one wakeup.

-Mike