From mboxrd@z Thu Jan 1 00:00:00 1970 From: Mike Galbraith Date: Thu, 22 May 2003 05:52:44 +0000 Subject: [Linux-ia64] Re: web page on O(1) scheduler Message-Id: List-Id: References: In-Reply-To: MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: linux-ia64@vger.kernel.org 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