From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1761027AbYAUQSH (ORCPT ); Mon, 21 Jan 2008 11:18:07 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1756263AbYAUQR5 (ORCPT ); Mon, 21 Jan 2008 11:17:57 -0500 Received: from mga07.intel.com ([143.182.124.22]:29656 "EHLO azsmga101.ch.intel.com" rhost-flags-OK-OK-OK-FAIL) by vger.kernel.org with ESMTP id S1755813AbYAUQR4 (ORCPT ); Mon, 21 Jan 2008 11:17:56 -0500 X-ExtLoop1: 1 X-IronPort-AV: E=Sophos;i="4.25,227,1199692800"; d="scan'208";a="369636140" Message-ID: <4794C554.4000200@linux.intel.com> Date: Mon, 21 Jan 2008 08:16:20 -0800 From: Arjan van de Ven User-Agent: Thunderbird 1.5.0.14 (Windows/20071210) MIME-Version: 1.0 To: KOSAKI Motohiro CC: Linux Kernel Mailing List , Linus Torvalds , Ingo Molnar , Andrew Morton Subject: Re: LatencyTOP infrastructure patch References: <4790E3A6.7060807@linux.intel.com> <20080118093943.0048d0f7@laptopd505.fenrus.org> <20080121170415.125B.KOSAKI.MOTOHIRO@jp.fujitsu.com> In-Reply-To: <20080121170415.125B.KOSAKI.MOTOHIRO@jp.fujitsu.com> Content-Type: text/plain; charset=ISO-8859-1; format=flowed Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org KOSAKI Motohiro wrote: > Hi > >> +static void __sched >> +account_global_scheduler_latency(struct task_struct *tsk, int usecs) >> +{ >> + int i; >> + int firstnonnull = MAXLR + 1; >> + >> + if (!tsk->latency_reason.reason) >> + return; >> + >> + /* skip kernel threads for now */ >> + if (!tsk->mm) >> + return; > > Why do you ignore kernel thread? > > may be, some network filesystem use kernel thread for local I/O. > What do you think it? kernel threads (by themselves) don't tend to result in user visible latency... at least that's my assumption so far... if you think I'm wrong... I'm open to be shown that we should count them.