Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1758950AbYLQHeV (ORCPT ); Wed, 17 Dec 2008 02:34:21 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751548AbYLQHeL (ORCPT ); Wed, 17 Dec 2008 02:34:11 -0500 Received: from mail-bw0-f21.google.com ([209.85.218.21]:41158 "EHLO mail-bw0-f21.google.com" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751258AbYLQHeK (ORCPT ); Wed, 17 Dec 2008 02:34:10 -0500 DomainKey-Signature: a=rsa-sha1; c=nofws; d=googlemail.com; s=gamma; h=message-id:date:from:reply-to:to:subject:cc:in-reply-to :mime-version:content-type:content-transfer-encoding :content-disposition:references; b=YRns74qPOlzanWaaURnZlXiU33GwJ8Fh8Pjg12fOKA4vS1ukRxHe1hbCDtBInudByE PAxpBuuQITwJBuIf1tiSYNi7bjJS6Gw1w3PIaWFhEONNc/knTpDnrp/o7EnT6kw6ewa1 JmJl4MzVGFxf5A570CcsHUo2PnfziBkbfq9SE= Message-ID: <7c86c4470812162334v4515563fq8f27d5b6f381108e@mail.gmail.com> Date: Wed, 17 Dec 2008 08:34:07 +0100 From: "stephane eranian" Reply-To: eranian@gmail.com To: "Paul Mackerras" Subject: Re: [patch] Performance Counters for Linux, v4 Cc: "Peter Zijlstra" , "Ingo Molnar" , linux-kernel@vger.kernel.org, "Thomas Gleixner" , "Andrew Morton" , "Eric Dumazet" , "Robert Richter" , "Arjan van de Ven" , "Peter Anvin" , "David S. Miller" , perfctr-devel@lists.sourceforge.net In-Reply-To: <18760.13407.568536.198724@cargo.ozlabs.ibm.com> MIME-Version: 1.0 Content-Type: text/plain; charset=UTF-8 Content-Transfer-Encoding: 7bit Content-Disposition: inline References: <20081214212829.GA9435@elte.hu> <18758.18810.350923.806445@cargo.ozlabs.ibm.com> <1229437341.7025.11.camel@twins> <18760.13407.568536.198724@cargo.ozlabs.ibm.com> Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Paul, On Wed, Dec 17, 2008 at 12:06 AM, Paul Mackerras wrote: > > I think we need a "full-time" attribute for counters and groups that > says "I need to be on the whole time", where "whole time" means > whenever the task is running, for a per-task counter or group, or > continuously for per-cpu counters/groups. > Who would want not to be the only owner of the PMU? Especially when you know that if you don't, you may be sharing it with another user who may perturb your measurement, for instance because of heavy sampling while you are just counting. It is a tradeoff between flexibility and accuracy. Which one is more important? -- 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/