From mboxrd@z Thu Jan 1 00:00:00 1970 Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752531Ab0BIER6 (ORCPT ); Mon, 8 Feb 2010 23:17:58 -0500 Received: from mx2.mail.elte.hu ([157.181.151.9]:46922 "EHLO mx2.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750856Ab0BIER5 (ORCPT ); Mon, 8 Feb 2010 23:17:57 -0500 Date: Tue, 9 Feb 2010 05:17:39 +0100 From: Ingo Molnar To: Cyrill Gorcunov Cc: Peter Zijlstra , Stephane Eranian , Frederic Weisbecker , Don Zickus , LKML Subject: Re: [RFC perf,x86] P4 PMU early draft Message-ID: <20100209041739.GA11280@elte.hu> References: <20100208184504.GB5130@lenovo> MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Disposition: inline In-Reply-To: <20100208184504.GB5130@lenovo> User-Agent: Mutt/1.5.20 (2009-08-17) X-ELTE-SpamScore: -2.0 X-ELTE-SpamLevel: X-ELTE-SpamCheck: no X-ELTE-SpamVersion: ELTE 2.0 X-ELTE-SpamCheck-Details: score=-2.0 required=5.9 tests=BAYES_00 autolearn=no SpamAssassin version=3.2.5 -2.0 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 * Cyrill Gorcunov wrote: > Hi all, > > first of all the patches are NOT for any kind of inclusion. It's not ready > yet. More likely I'm asking for glance review, ideas, criticism. A quick question: does the code produce something on a real P4? (possibly only running with a single event - but even that would be enough.) > The main problem in implementing P4 PMU is that it has much more > restrictions for event to MSR mapping. [...] One possibly simpler approach might be to represent the P4 PMU via a maximum _two_ generic events only. Last i looked at the many P4 events, i've noticed that generally you can create any two events. (with a few exceptions) Once you start trying to take advantage of the more than a dozen seemingly separate counters, additional non-trivial constraints apply. So if we only allowed a maximum of _two_ generic events (like say a simple Core2 has, so it's not a big restriction at all), we wouldnt have to map all the constraints, we'd only have to encode the specific event-to-MSR details. (which alone is quite a bit of work as well.) We could also use the new constraints code to map them all, of course - it will certainly be more complex to implement. Hm? Ingo