From mboxrd@z Thu Jan 1 00:00:00 1970 From: Ingo Molnar Subject: Re: [PATCH V3 0/6] Generalise ARM perf-events backend for oprofile Date: Mon, 13 Sep 2010 10:51:37 +0200 Message-ID: <20100913085137.GE23741@elte.hu> References: <20100913075025.GA14882@console-pimps.org> Mime-Version: 1.0 Content-Type: text/plain; charset=us-ascii Return-path: Received: from mx3.mail.elte.hu ([157.181.1.138]:57812 "EHLO mx3.mail.elte.hu" rhost-flags-OK-OK-OK-OK) by vger.kernel.org with ESMTP id S1752507Ab0IMIv6 (ORCPT ); Mon, 13 Sep 2010 04:51:58 -0400 Content-Disposition: inline In-Reply-To: <20100913075025.GA14882@console-pimps.org> Sender: linux-arch-owner@vger.kernel.org List-ID: To: Matt Fleming Cc: Marc Titinger , robert.richter@amd.com, linux-arch@vger.kernel.org, linux@arm.linux.org.uk, linux-sh@vger.kernel.org, peterz@infradead.org, fweisbec@gmail.com, will.deacon@arm.com, acme@redhat.com, lethal@linux-sh.org, linux-arm-kernel@lists.infradead.org * Matt Fleming wrote: > On Mon, Sep 13, 2010 at 09:13:32AM +0200, Marc Titinger wrote: > > > > Hi, > > > > I'm just being curious : do these patches change the way those chips > > should be supported, that do not have a PMU-like IP, but implement > > PC-sampling thanks to a general purpose timer (not the system timer) > > ? > > CPUs that do not have a PMU are not required to use the perf-events > oprofile backend, it is entirely optional. The pc-sampling timer in > oprofile is not affected by this series. It should still work fine though: a generalized oprofile backend should simply use hrtimer based events. That also has a chance to be higher quality than the system time fallback, on PMU-less (but high-res-timer capable) systems. Thanks, Ingo