Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S965452AbXECHqE (ORCPT ); Thu, 3 May 2007 03:46:04 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S965686AbXECHqE (ORCPT ); Thu, 3 May 2007 03:46:04 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:39531 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S965452AbXECHqB (ORCPT ); Thu, 3 May 2007 03:46:01 -0400 Date: Thu, 3 May 2007 09:45:52 +0200 From: Ingo Molnar To: Al Boldi Cc: linux-kernel@vger.kernel.org Subject: Re: [patch] CFS scheduler, -v7 Message-ID: <20070503074552.GA14960@elte.hu> References: <200704300820.49078.a1426z@gawab.com> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200704300820.49078.a1426z@gawab.com> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.1.7 -2.0 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1766 Lines: 45 * Al Boldi wrote: > > i'm pleased to announce release -v7 of the CFS scheduler patchset. > > (The main goal of CFS is to implement "desktop scheduling" with as > > high quality as technically possible.) > : > : > > As usual, any sort of feedback, bugreport, fix and suggestion is > > more than welcome, > > This one seems on par with SD, [...] excellent :-) > [...] but there are still some nice issues. > > Try running 3 chew.c's, then renicing one to -10, starves others for > some seconds while switching prio-level. Now renice it back to 10, it > starves for up to 45sec. ok - to make sure i understood you correctly: does this starvation only occur right when you renice it (when switching prio levels), and it gets rectified quickly once they get over a few reschedules? > Also, nice levels are only effective on every other step; ie: > ... -3/-2 , -1/0 , 1/2 ... yields only 20 instead of 40 prio-levels. yeah - this is a first-approximation thing. Some background: in the upstream scheduler (and in SD) nice levels are linearly scaled, while in CFS they are exponentially scaled. I did this because i believe exponential is more logical: regardless of which nice level a task uses, if it goes +2 nice levels up then it will halve its "fair CPU share". So for example the CPU consumption delta between nice 0 and nice +10 is 1/32 - and so is the delta between -5 and +5, -10 and -5, etc. This makes nice levels _alot_ more potent than upstream's linear approach. Ingo - To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@vger.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/