From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1161364AbXDXHAS (ORCPT ); Tue, 24 Apr 2007 03:00:18 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1161427AbXDXHAS (ORCPT ); Tue, 24 Apr 2007 03:00:18 -0400 Received: from an-out-0708.google.com ([209.85.132.245]:37842 "EHLO an-out-0708.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1161364AbXDXHAP (ORCPT ); Tue, 24 Apr 2007 03:00:15 -0400 DomainKey-Signature: a=rsa-sha1; c=nofws; d=gmail.com; s=beta; h=received:from:organization:to:subject:date:user-agent:cc:references:in-reply-to:mime-version:content-type:content-transfer-encoding:content-disposition:message-id; b=sGaTObQ7vs7gJhAJDs2OjQB6NMNFhofbhKFa5T0iaWrs48NzAcMCr5+SUntnnplkv2Nqw+5fcYEEFa+46VhTMgqzAZb2IJGjexThKm0AzFcYgSNzl/MoDD0RCwRRGQnUgsUJzUEI4tfnTn+lN4fRTYeoQMwIvONT97Uaktmmq/c= From: Gene Heskett Organization: Organization? very little To: Ingo Molnar Subject: Re: [REPORT] cfs-v4 vs sd-0.44 Date: Tue, 24 Apr 2007 03:00:07 -0400 User-Agent: KMail/1.9.6 Cc: Peter Williams , Arjan van de Ven , Linus Torvalds , Nick Piggin , Juliusz Chroboczek , Con Kolivas , ck list , Bill Davidsen , Willy Tarreau , William Lee Irwin III , linux-kernel@vger.kernel.org, Andrew Morton , Mike Galbraith , Thomas Gleixner , caglar@pardus.org.tr References: <200704220959.34978.kernel@kolivas.org> <462DA1E8.9080201@bigpond.net.au> <20070424063633.GA17257@elte.hu> In-Reply-To: <20070424063633.GA17257@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="iso-8859-1" Content-Transfer-Encoding: 7bit Content-Disposition: inline Message-Id: <200704240300.07689.gene.heskett@gmail.com> Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org On Tuesday 24 April 2007, Ingo Molnar wrote: >* Peter Williams wrote: >> > The cases are fundamentally different in behavior, because in the >> > first case, X hardly consumes the time it would get in any scheme, >> > while in the second case X really is CPU bound and will happily >> > consume any CPU time it can get. >> >> Which still doesn't justify an elaborate "points" sharing scheme. >> Whichever way you look at that that's just another way of giving X >> more CPU bandwidth and there are simpler ways to give X more CPU if it >> needs it. However, I think there's something seriously wrong if it >> needs the -19 nice that I've heard mentioned. > >Gene has done some testing under CFS with X reniced to +10 and the >desktop still worked smoothly for him. As a data point here, and probably nothing to do with X, but I did manage to lock it up, solid, reset button time tonight, by wanting 'smart' to get done with an update session after amanda had started. I took both smart processes I could see in htop all the way to -19, but when it was about done about 3 minutes later, everything came to an instant, frozen, reset button required lockup. I should have stopped at -17 I guess. :( >So CFS does not 'need' a reniced >X. There are simply advantages to negative nice levels: for example >screen refreshes are smoother on any scheduler i tried. BUT, there is a >caveat: on non-CFS schedulers i tried X is much more prone to get into >'overscheduling' scenarios that visibly hurt X's performance, while on >CFS there's a max of 1000-1500 context switches a second at nice -10. >(which, considering the cost of a context switch is well under 1% >overhead.) > >So, my point is, the nice level of X for desktop users should not be set >lower than a low limit suggested by that particular scheduler's author. >That limit is scheduler-specific. Con i think recommends a nice level of >-1 for X when using SD [Con, can you confirm?], while my tests show that >if you want you can go as low as -10 under CFS, without any bad >side-effects. (-19 was a bit too much) > >> [...] You might as well just run it as a real time process. > >hm, that would be a bad idea under any scheduler (including CFS), >because real time processes can starve other processes indefinitely. > > Ingo -- Cheers, Gene "There are four boxes to be used in defense of liberty: soap, ballot, jury, and ammo. Please use in that order." -Ed Howdershelt (Author) I have discovered that all human evil comes from this, man's being unable to sit still in a room. -- Blaise Pascal