Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752075AbZDMRTq (ORCPT ); Mon, 13 Apr 2009 13:19:46 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751483AbZDMRTg (ORCPT ); Mon, 13 Apr 2009 13:19:36 -0400 Received: from mx3.mail.elte.hu ([157.181.1.138]:42694 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751200AbZDMRTf (ORCPT ); Mon, 13 Apr 2009 13:19:35 -0400 Date: Mon, 13 Apr 2009 19:18:53 +0200 From: Ingo Molnar To: Linus Torvalds Cc: Valdis.Kletnieks@vt.edu, Mike Travis , Andrew Morton , Linux Kernel Mailing List , mm-commits@vger.kernel.org, Rusty Russell , Dave Jones Subject: Re: mmotm 2009-04-10-02-21 uploaded - forkbombed by work_for_cpu Message-ID: <20090413171853.GA4601@elte.hu> References: <200904100922.n3A9MOIV013828@imap1.linux-foundation.org> <4609.1239456126@turing-police.cc.vt.edu> 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-VirusStatus: clean 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=3.2.3 -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 Content-Length: 1575 Lines: 42 * Linus Torvalds wrote: > So I do think Andrew's commit is broken and we should think about > it a bit more, but I also think that Valdis' problem comes from > acpi-cpufreq just being damn stupid. Doing a > smp_call_function_single() to read two MSR's is going to be a > _lot_ more efficient than doing that crazy work_on_cpu() for that. > > So the _real_ problem came through the commits like > > cpufreq: use work_on_cpu in acpi-cpufreq.c for drv_read and drv_write > cpumask: use work_on_cpu in acpi-cpufreq.c for read_measured_perf_ctrs > > that were meant to reduce stack usage with big cpu masks. And > sure, the _old_ way of doing it was also stupid (it rescheduled > the process to the other CPU by using cpus_allowed()). > > Mike, Ingo? I think Andrew has a stack of fixes queued up, one of which should solve this problem too - which Mike tested - as the commit from Andrew has caused another regression as well. There's no sha1 - the patch is in this thread on lkml: sysbench(oltp)+mysql 10% regression with 2.6.30-rc1 | From: Andrew Morton | | Atttempting to rid us of the problematic work_on_cpu(). Just use | smp_call_fuction_single() here. | | This repairs a 10% sysbench(oltp)+mysql regression which Mike | reported, 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/