From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1750797AbWDSIh2 (ORCPT ); Wed, 19 Apr 2006 04:37:28 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750785AbWDSIh1 (ORCPT ); Wed, 19 Apr 2006 04:37:27 -0400 Received: from rhlx01.fht-esslingen.de ([129.143.116.10]:8098 "EHLO rhlx01.fht-esslingen.de") by vger.kernel.org with ESMTP id S1750797AbWDSIh0 (ORCPT ); Wed, 19 Apr 2006 04:37:26 -0400 Date: Wed, 19 Apr 2006 10:37:24 +0200 From: Andreas Mohr To: Con Kolivas Cc: Al Boldi , ck list , Mike Galbraith , linux-kernel@vger.kernel.org Subject: Re: [ck] Re: [patch][rfc] quell interactive feeding frenzy Message-ID: <20060419083724.GA7329@rhlx01.fht-esslingen.de> References: <200604112100.28725.kernel@kolivas.org> <200604160923.00047.kernel@kolivas.org> <20060416184426.GA15642@rhlx01.fht-esslingen.de> <200604171008.10067.kernel@kolivas.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <200604171008.10067.kernel@kolivas.org> User-Agent: Mutt/1.4.2.1i X-Priority: none Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Hi, On Mon, Apr 17, 2006 at 10:08:08AM +1000, Con Kolivas wrote: > On Monday 17 April 2006 04:44, Andreas Mohr wrote: > > Hi, > > > > On Sun, Apr 16, 2006 at 09:22:59AM +1000, Con Kolivas wrote: > > > The current value, 6ms at 1000HZ, is chosen because it's the largest > > > value that can schedule a task in less than normal human perceptible > > > range when two competing heavily cpu bound tasks are the same priority. > > > At 250HZ it works out to 7.5ms and 10ms at 100HZ. Ironically in my > > > experimenting I found the cpu cache improvements become much less > > > significant above 7ms so I'm very happy with this compromise. > > > > Heh, this part is *EXACTLY* a fully sufficient explanation of what I was > > wondering about myself just these days ;) > > (I'm experimenting with different timeslice values on my P3/450 to verify > > what performance impact exactly it has) > > However with a measly 256kB cache it probably doesn't matter too much, > > I think. > > > > But I think it's still important to mention that your perception might be > > twisted by your P4 limitation (no testing with slower and really slow > > machines). > > You underestimate me. Those cpu cache effects were performance effects > measured down to a PII 233, but all were i386 architecture. As for > "perception" this isn't my testing I'm talking about; these are > neuropsychiatric tests that have nothing to do with pcs or what processor you > use ;) OK, but I was not worrying about the interactivity aspects, rather the performance aspects (GUI updates of KDE 3.5.2 on P3/450/256MB on Ubuntu are about as slow as medium-hot lava). While of course it's mostly KDE (and probably also the S3 Savage driver/card) which is to blame here, I'm trying to first do as much as possible at kernel level before eventually going higher up the chain... Andreas