From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752627AbZHZSFg (ORCPT ); Wed, 26 Aug 2009 14:05:36 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752558AbZHZSFf (ORCPT ); Wed, 26 Aug 2009 14:05:35 -0400 Received: from mx2.mail.elte.hu ([157.181.151.9]:36901 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752513AbZHZSFe (ORCPT ); Wed, 26 Aug 2009 14:05:34 -0400 Date: Wed, 26 Aug 2009 20:04:07 +0200 From: Ingo Molnar To: Christoph Lameter Cc: Peter Zijlstra , raz ben yehuda , Maxim Levitsky , Chris Friesen , Mike Galbraith , riel@redhat.com, andrew motron , wiseman@macs.biu.ac.il, lkml , linux-rt-users@vger.kernel.org Subject: Re: RFC: THE OFFLINE SCHEDULER Message-ID: <20090826180407.GA13632@elte.hu> References: <4A943A00.9080609@nortel.com> <1251264700.7538.1178.camel@twins> <1251282598.3514.20.camel@raz> <1251297910.1791.22.camel@maxim-laptop> <1251298443.4791.7.camel@raz> <1251300625.18584.18.camel@twins> <1251302598.18584.31.camel@twins> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: User-Agent: Mutt/1.5.18 (2008-05-17) X-ELTE-SpamScore: -1.5 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-1.5 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -1.5 BAYES_00 BODY: Bayesian spam probability is 0 to 1% [score: 0.0000] Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org * Christoph Lameter wrote: > On Wed, 26 Aug 2009, Peter Zijlstra wrote: > > > On Wed, 2009-08-26 at 11:41 -0400, Christoph Lameter wrote: > > > On Wed, 26 Aug 2009, Peter Zijlstra wrote: > > > > > > > Why waste a whole cpu for something that could be done by part of one? > > > > > > Because of latency and performance requirements > > > > Latency is the only one, and yes people have been using hacks > > like this, I've also earlier mentioned RTAI, RTLinux and > > L4-Linux which basically do the same thing. > > > > The problem is, that its not linux, you cannot run something on > > a these off-cores and use the same functionality as linux, if > > you could it'd not be offline. > > Right. We discussed this. Why are you repeating the same old > arguments? The thing is, you have cut out (and have not replied to) this crutial bit of what Peter wrote: > > The past year or so you've been whining about the tick latency, > > and I've seen exactly _0_ patches from you slimming down the > > work done in there, even though I pointed out some obvious > > things that could be done. ... which pretty much settles the issue as far as i'm concerned. If you were truly interested in a constructive solution to lower latencies in Linux you should have sent patches already for the low hanging fruits Peter pointed out. Ingo