Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1754634AbZAZWLW (ORCPT ); Mon, 26 Jan 2009 17:11:22 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1751962AbZAZWLO (ORCPT ); Mon, 26 Jan 2009 17:11:14 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:36687 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1751745AbZAZWLN (ORCPT ); Mon, 26 Jan 2009 17:11:13 -0500 Date: Mon, 26 Jan 2009 23:10:38 +0100 From: Ingo Molnar To: "Luck, Tony" Cc: Corey Ashford , Peter Zijlstra , Andrew Morton , Papi , "David S. Miller" , Mike Galbraith , "linux-kernel@vger.kernel.org" , Eric Dumazet , Paul Mackerras , Peter Anvin , "eranian@gmail.com" , Thomas Gleixner , "perfmon2-devel@lists.sourceforge.net" , Arjan van de Ven Subject: Re: [perfmon2] [announce] Performance Counters for Linux, v6 Message-ID: <20090126221038.GA7440@elte.hu> References: <20090121185021.GA8852@elte.hu> <497D0C81.5040406@linux.vnet.ibm.com> <7c86c4470901260113r4db6b15cpa0fa88ab3f8a516c@mail.gmail.com> <20090126151746.GH9128@elte.hu> <497E0B55.4050408@linux.vnet.ibm.com> <57C9024A16AD2D4C97DC78E552063EA35F1F9374@orsmsx505.amr.corp.intel.com> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <57C9024A16AD2D4C97DC78E552063EA35F1F9374@orsmsx505.amr.corp.intel.com> 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: 1112 Lines: 27 * Luck, Tony wrote: > > - or the PMU capability is expressed as a special counter type (if it's > > useful enough) - and then either the write() method or ioctl is extended > > to express attributes we want to set/change while a counter is running. > > The product of: > {exotic PMU modes} * {creative performance measurement ideas} > > will produce a large number of candidates for these special counters (at > least on ia64 ... which has a large number of exotic PMU options). > > I don't think that I'm qualified to judge which of them are "useful > enough" to warrant a special counter type. it should certainly be done on a case by case basis. They need to be consciously exposed not just summarily exported to user-space, because PMU hw features have security implications so it has to be done all explicitly. 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/