From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S262336AbVGLEaf (ORCPT ); Tue, 12 Jul 2005 00:30:35 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S262337AbVGLEaf (ORCPT ); Tue, 12 Jul 2005 00:30:35 -0400 Received: from dvhart.com ([64.146.134.43]:10678 "EHLO localhost.localdomain") by vger.kernel.org with ESMTP id S262336AbVGLEad (ORCPT ); Tue, 12 Jul 2005 00:30:33 -0400 Date: Mon, 11 Jul 2005 21:30:33 -0700 From: "Martin J. Bligh" Reply-To: "Martin J. Bligh" To: Lee Revell Cc: Chris Friesen , Diego Calleja , azarah@nosferatu.za.org, akpm@osdl.org, cw@f00f.org, linux-kernel@vger.kernel.org, torvalds@osdl.org, christoph@lameter.org Subject: Re: [PATCH] i386: Selectable Frequency of the Timer Interrupt Message-ID: <188690000.1121142633@[10.10.2.4]> In-Reply-To: <1121141602.2632.31.camel@mindpipe> References: <200506231828.j5NISlCe020350@hera.kernel.org> <20050708214908.GA31225@taniwha.stupidest.org> <20050708145953.0b2d8030.akpm@osdl.org> <1120928891.17184.10.camel@lycan.lan> <1120932991.6488.64.camel@mindpipe> <20050709203920.394e970d.diegocg@gmail.com> <1120934466.6488.77.camel@mindpipe> <176640000.1121107087@flay> <1121113532.2383.6.camel@mindpipe> <42D2D912.3090505@nortel.com> <1121128260.2632.12.camel@mindpipe> <165840000.1121141256@[10.10.2.4]> <1121141602.2632.31.camel@mindpipe> X-Mailer: Mulberry/2.2.1 (Linux/x86) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Content-Disposition: inline Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org --Lee Revell wrote (on Tuesday, July 12, 2005 00:13:21 -0400): > On Mon, 2005-07-11 at 21:07 -0700, Martin J. Bligh wrote: >> >> --Lee Revell wrote (on Monday, July 11, 2005 20:30:59 -0400): >> >> > On Mon, 2005-07-11 at 14:39 -0600, Chris Friesen wrote: >> >> Lee Revell wrote: >> >> >> >> > Tickless + sub HZ timers is a win for everyone, the multimedia people >> >> > get better latency, and the laptop people get to run longer. >> >> >> >> IIRC it's not a win for many systems. Throughput goes down due to timer >> >> manipulation overhead. >> > >> > Makes sense. Anyway, this whole thread has been pretty hand wavey, I >> > propose that until we see some numbers from the HZ=250 advocates, we >> > leave the default alone. >> >> Odd. Since I showed you some numbers already ... and nobody from the latency >> side of the argument has come up with any? > > Sorry, I have not seen any. Got a link? Look back in the thread. It made kernel compiles about 5% faster on a fairly large box. I think the SGI people did it originally because it caused them even larger problems. I'm not saying their aren't arguments on both sides ... there are. I just agree with you there's a lot of hand-waving going on ... but probably not agreeing as to who it's coming from ;-) Some sort of comprimise has to be struck for now, until we get sub-HZ timers. I'd prefer 100, personally (I had that set as default in my tree for a long time). Some people would prefer 1000 or even more, maybe. 250/300 seems like a reasonable comprimise to me. Exactly what problems *does* it cause (in visible effect, not "timers are less granular"). Jittery audio/video? How much worse is it? M.