Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1755086AbZDRH70 (ORCPT ); Sat, 18 Apr 2009 03:59:26 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752814AbZDRH7S (ORCPT ); Sat, 18 Apr 2009 03:59:18 -0400 Received: from one.firstfloor.org ([213.235.205.2]:44778 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752796AbZDRH7R (ORCPT ); Sat, 18 Apr 2009 03:59:17 -0400 To: "Chris Friesen" Cc: Christoph Lameter , Peter Zijlstra , Ingo Molnar , linux-kernel@vger.kernel.org Subject: Re: Scheduler regression: Too frequent timer interrupts(?) From: Andi Kleen References: <1239951613.23397.4107.camel@laptop> <1239977776.23397.4590.camel@laptop> <1239979901.23397.4638.camel@laptop> <20090417153520.GA29968@elte.hu> <1239985426.23397.4757.camel@laptop> <20090417164918.GK8253@elte.hu> <1239991892.23397.4905.camel@laptop> <49E90F9D.5010308@nortel.com> Date: Sat, 18 Apr 2009 09:59:11 +0200 In-Reply-To: <49E90F9D.5010308@nortel.com> (Chris Friesen's message of "Fri, 17 Apr 2009 17:24:13 -0600") Message-ID: <87vdp2qto0.fsf@basil.nowhere.org> User-Agent: Gnus/5.1008 (Gnus v5.10.8) Emacs/22.3 (gnu/linux) MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 813 Lines: 21 "Chris Friesen" writes: > > Given that we're talking about tens of usecs of duration, statistical > sampling may not work all that well. He could just use oprofile with a small period. The minimum period for CPU_CLK_UNHALTED is 6000 (and it could be probably lowered by tweaking the events) oprofile counters on x86 can be configured to only count in ring 0 So you would get an entry every 6000 ring 0 cycles. That should give a pretty good picture where the kernel is spending time. -Andi -- ak@linux.intel.com -- Speaking for myself only. -- 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/