Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1752174AbYLOML6 (ORCPT ); Mon, 15 Dec 2008 07:11:58 -0500 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1750802AbYLOMLt (ORCPT ); Mon, 15 Dec 2008 07:11:49 -0500 Received: from ozlabs.org ([203.10.76.45]:45073 "EHLO ozlabs.org" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750793AbYLOMLt (ORCPT ); Mon, 15 Dec 2008 07:11:49 -0500 MIME-Version: 1.0 Content-Type: text/plain; charset=us-ascii Content-Transfer-Encoding: 7bit Message-ID: <18758.18810.350923.806445@cargo.ozlabs.ibm.com> Date: Mon, 15 Dec 2008 23:11:38 +1100 From: Paul Mackerras To: Ingo Molnar Cc: linux-kernel@vger.kernel.org, Thomas Gleixner , Andrew Morton , Stephane Eranian , Eric Dumazet , Robert Richter , Arjan van de Ven , Peter Anvin , Peter Zijlstra , "David S. Miller" , perfctr-devel@lists.sourceforge.net Subject: Re: [patch] Performance Counters for Linux, v4 In-Reply-To: <20081214212829.GA9435@elte.hu> References: <20081214212829.GA9435@elte.hu> X-Mailer: VM 8.0.9 under Emacs 22.2.1 (i486-pc-linux-gnu) Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 1232 Lines: 26 Ingo Molnar writes: > We are pleased to announce the v4 release of our performance counters > subsystem implementation. Looking at the code, I am wondering what you are planning to do to support machines that have constraints on what sets of events can be counted simultaneously. Currently you have the core code calling counter->hw_ops->hw_perf_counter_enable which can't return an error. The core expects it to be able to add any counter regardless of what event it's counting, subject only to a maximum number of counters. I assume you're going to change that. I think the core should put together a list of counters and counter groups that it would like to have on the PMU simultaneously and then make one call to the arch layer to ask if that is possible. That could either return success or failure. If it returns failure then the core needs to ask for something less, or something different. I'm not sure how the core should choose what to ask for instead, though. Paul. -- 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/