From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1759321AbYC0Mfj (ORCPT ); Thu, 27 Mar 2008 08:35:39 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756012AbYC0Mfb (ORCPT ); Thu, 27 Mar 2008 08:35:31 -0400 Received: from brick.kernel.dk ([87.55.233.238]:21077 "EHLO kernel.dk" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755221AbYC0Mfa (ORCPT ); Thu, 27 Mar 2008 08:35:30 -0400 Date: Thu, 27 Mar 2008 13:35:25 +0100 From: Jens Axboe To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, npiggin@suse.de, paulus@samba.org, tglx@linutronix.de, mingo@redhat.com, tony.luck@intel.com, Alan.Brunelle@hp.com Subject: Re: [PATCH 0/5] Generic smp_call_function(), improvements, and smp_call_function_single() Message-ID: <20080327123525.GN12346@kernel.dk> References: <1205927772-31401-1-git-send-email-jens.axboe@oracle.com> <20080321095343.GA21409@elte.hu> <20080321131558.GA15355@kernel.dk> <20080327100802.GD15003@elte.hu> <20080327103707.GH12346@kernel.dk> <20080327104359.GC26725@elte.hu> <20080327120244.GL12346@kernel.dk> <20080327123213.GC21894@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20080327123213.GC21894@elte.hu> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org On Thu, Mar 27 2008, Ingo Molnar wrote: > > * Jens Axboe wrote: > > > > i'd love to be able to run/pull something simple that enables me to > > > replicate the measurements you did on a generic PC [without having > > > to hit any real IO hardware which would put any context switching > > > effects down into the noise category]. > > > > You can pull io-cpu-affinity or io-cpu-affinity-kthread from > > git://git.kernel.dk/linux-2.6-block.git - or just see the two attached > > patches, apply either one to current -git to test it. > > another stupid question: what should i run in user-space to replicate > your "3 usecs versus 2 usecs" result? io-affinity-ipi.patch seems to > have no self-benchmarking capability at first sight. (I'd rather not try > and cook up anything myself - i'd like to reproduce the workload you > think is relevant for your IO affinity purposes.) Best would be to have > a Kconfig based self-test that just runs during bootup if i boot a > bzImage. (laziness rules - and this way i could also track performance > regressions more easily, by looking at historic serial logs.) I didn't do those numbers - Alan, when you timed the kthread vs ipi "wake up", what did you use? I'm guessing some hacked in test, perhaps you can pass that to Ingo? -- Jens Axboe