Return-Path: Received: (majordomo@vger.kernel.org) by vger.kernel.org via listexpand id S1753675AbZG1HYG (ORCPT ); Tue, 28 Jul 2009 03:24:06 -0400 Received: (majordomo@vger.kernel.org) by vger.kernel.org id S1752009AbZG1HYF (ORCPT ); Tue, 28 Jul 2009 03:24:05 -0400 Received: from viefep17-int.chello.at ([62.179.121.37]:34864 "EHLO viefep17-int.chello.at" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1750983AbZG1HYE (ORCPT ); Tue, 28 Jul 2009 03:24:04 -0400 X-SourceIP: 213.93.53.227 Subject: Re: [RFC][PATCH 5/5] perfcounter: Add support for kernel hardware breakpoints From: Peter Zijlstra To: Frederic Weisbecker Cc: Ingo Molnar , LKML , Steven Rostedt , Thomas Gleixner , Mike Galbraith , Paul Mackerras , Arnaldo Carvalho de Melo , Lai Jiangshan , Anton Blanchard , Li Zefan , Zhaolei , KOSAKI Motohiro , Mathieu Desnoyers , "K . Prasad" , Alan Stern In-Reply-To: <20090728001844.GA5147@nowhere> References: <1248109687-7808-1-git-send-email-fweisbec@gmail.com> <1248109687-7808-6-git-send-email-fweisbec@gmail.com> <1248354493.26273.2.camel@twins> <1248445569.6987.74.camel@twins> <20090724174723.GA11985@nowhere> <1248519416.5780.12.camel@laptop> <20090725141918.GA5295@nowhere> <1248538972.5780.25.camel@laptop> <20090728001844.GA5147@nowhere> Content-Type: text/plain Date: Tue, 28 Jul 2009 09:26:40 +0200 Message-Id: <1248766000.6987.2759.camel@twins> Mime-Version: 1.0 X-Mailer: Evolution 2.26.1 Content-Transfer-Encoding: 7bit Sender: linux-kernel-owner@vger.kernel.org List-ID: X-Mailing-List: linux-kernel@vger.kernel.org Content-Length: 928 Lines: 21 On Tue, 2009-07-28 at 02:18 +0200, Frederic Weisbecker wrote: > > I still don't understand why it is needed to reserve breakpoints for > a group of monitored tasks. Once they have registered their breakpoints, > the number of necessary hardware registers for these will be available > every time the task is scheduled. Its possible to create >4 breakpoint counters. We time-share them. The only constraint we have is that those within a group should be on the 'PMU' at the same time. If you have no groups, a single available breakpoint slot should suffice for any configuration (although more is better), but if you get groups you have to guarantee your created group can run. -- 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/