From mboxrd@z Thu Jan 1 00:00:00 1970 From: Matt Fleming Date: Mon, 13 Sep 2010 11:04:44 +0000 Subject: Re: [PATCH V3 0/6] Generalise ARM perf-events backend for oprofile Message-Id: <20100913110444.GB14882@console-pimps.org> List-Id: References: <20100913075025.GA14882@console-pimps.org> <20100913085137.GE23741@elte.hu> In-Reply-To: <20100913085137.GE23741@elte.hu> MIME-Version: 1.0 Content-Type: text/plain; charset="us-ascii" Content-Transfer-Encoding: 7bit To: Ingo Molnar 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 On Mon, Sep 13, 2010 at 10:51:37AM +0200, Ingo Molnar wrote: > > * 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. Yeah, that's a good point. It would make a nice addition to this patch series. I may get chance to take a look at it at some point.