From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1756805Ab0I3Rgz (ORCPT ); Thu, 30 Sep 2010 13:36:55 -0400 Received: from one.firstfloor.org ([213.235.205.2]:45306 "EHLO one.firstfloor.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1755918Ab0I3Rgy (ORCPT ); Thu, 30 Sep 2010 13:36:54 -0400 From: Andi Kleen To: Venkatesh Pallipadi Cc: Peter Zijlstra , Ingo Molnar , "H. Peter Anvin" , Thomas Gleixner , Balbir Singh , linux-kernel@vger.kernel.org, Paul Turner , Eric Dumazet Subject: Re: Proper kernel irq time accounting -v3 References: <1285788096-29471-1-git-send-email-venki@google.com> <8762xnwtjn.fsf@basil.nowhere.org> Date: Thu, 30 Sep 2010 19:36:52 +0200 In-Reply-To: (Venkatesh Pallipadi's message of "Thu, 30 Sep 2010 09:37:17 -0700") Message-ID: <87lj6juo97.fsf@basil.nowhere.org> User-Agent: Gnus/5.13 (Gnus v5.13) Emacs/23.1 (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 Venkatesh Pallipadi writes: > > Yes. Overhead will be RDTSC. > notsc is a boot option that will disable this. I didn't want to have a notsc is a very heavy hammer. > specific run time option to disable this as we would already have > other RDTSC users like native_sched_clock. Do you think we need a > specific option to disable this feature? I don't like adding a runtime > option because it complicates the code a bit (to handle things like > someone turning it off and turning it on later, etc). How about some benchmarks on a known slow TSC system, like a P4? If you can't measure it even with high interrupt loads it is probably not relevant. If it is it would be better to have a on/off switch. -Andi -- ak@linux.intel.com -- Speaking for myself only.