Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1422852AbXBASFO (ORCPT ); Thu, 1 Feb 2007 13:05:14 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1422867AbXBASFO (ORCPT ); Thu, 1 Feb 2007 13:05:14 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:36406 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1422852AbXBASFM (ORCPT ); Thu, 1 Feb 2007 13:05:12 -0500 Date: Thu, 1 Feb 2007 19:02:47 +0100 From: Ingo Molnar To: Mark Lord Cc: Christoph Hellwig , Zach Brown , linux-kernel@vger.kernel.org, linux-aio@kvack.org, Suparna Bhattacharya , Benjamin LaHaise , Linus Torvalds Subject: Re: [PATCH 2 of 4] Introduce i386 fibril scheduling Message-ID: <20070201180247.GA561@elte.hu> References: <20070201083611.GC18233@elte.hu> <20070201130234.GA15257@elte.hu> <20070201131903.GA24683@infradead.org> <20070201135215.GA23477@elte.hu> <45C21FCC.7040406@rtr.ca> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <45C21FCC.7040406@rtr.ca> User-Agent: Mutt/1.4.2.2i X-ELTE-VirusStatus: clean X-ELTE-SpamScore: -2.8 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.8 required=5.9 tests=ALL_TRUSTED,BAYES_40 autolearn=no SpamAssassin version=3.0.3 -3.3 ALL_TRUSTED Did not pass through any untrusted hosts 0.5 BAYES_40 BODY: Bayesian spam probability is 20 to 40% [score: 0.3314] Sender: linux-kernel-owner@vger.kernel.org X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1964 Lines: 47 * Mark Lord wrote: > >also, we context-switch kernel threads in 350 nsecs on current > >hardware and the -rt kernel is certainly happy with that and runs all > >hardirqs > > Ingo, how relevant is that "350 nsecs on current hardware" claim? > > I don't mean that in a bad way, but my own experience suggests that > most people doing real hard RT (or tight soft RT) are not doing it on > x86 architectures. But rather on lowly 1GHz (or less) ARM based > processors and the like. it's not relevant to those embedded boards, but it's relevant to the AIO discussion, which centers around performance. > For RT issues, those are the platforms I care more about, as those are > the ones that get embedded into real-time devices. yeah. Nevertheless if you want to use -rt on your desktop (under Fedora 4/5/6) you can track an rpmized+distroized full kernel package quite easily, via 3 easy commands: cd /etc/yum.repos.d wget http://people.redhat.com/~mingo/realtime-preempt/rt.repo yum install kernel-rt.x86_64 # on x86_64 yum install kernel-rt # on i686 which is closely tracking latest upstream -git. (for example, the current kernel-rt-2.6.20-rc7.1.rt3.0109.i686.rpm is based on 2.6.20-rc7-git1, so if you want to run a kernel rpm that has all of Linus' latest commits from yesterday, this might be for you.) it's rumored to be a quite smooth kernel ;-) So in this sense, because this also runs on all my testboxes by default, it matters on modern hardware too, at least to me. Today's commodity hardware is tomorrow's embedded hardware. If a kernel is good on today's colorful desktop hardware then it will be perfect for tomorrow's embedded hardware. 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/