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Date: Wed, 12 Oct 2011 09:04:02 +0200 From: Ingo Molnar <mingo@...e.hu> To: Robert Richter <robert.richter@....com> Cc: Peter Zijlstra <peterz@...radead.org>, Stephane Eranian <eranian@...gle.com>, LKML <linux-kernel@...r.kernel.org>, Don Zickus <dzickus@...hat.com>, acme <acme@...stprotocols.net>, Frédéric Weisbecker <fweisbec@...il.com>, Thomas Gleixner <tglx@...utronix.de> Subject: Re: [V3][PATCH 0/7] perf, x86: Implement AMD IBS * Robert Richter <robert.richter@....com> wrote: > On 04.10.11 04:54:09, Ingo Molnar wrote: > > So the whole IBS thing looks quite unintegrated to me - and that's > > partly because the hw is admittedly weird. The way we could perhaps > > live with it upstream is two conditions: > > > > - Testable IBS user-space code a bit more prominently integrated > > than having to go down into a cellar with no working lights and > > finding the code on display in tools/perf/Documentation/examples/ > > on the bottom of a locked filing cabinet stuck in a disused > > lavatory with a sign on the door saying 'Beware of the Leopard.' > > With Lin Ming's patch > > [PATCH v2 6/6] perf tool: Parse general/raw events from sysfs > > you can use perf record to collect IBS samples, e.g.: > > # perf record -e ibs_fetch:r0 -c 100000 -a bash -c someload > [ perf record: Woken up 3 times to write data ] > [ perf record: Captured and wrote 2.004 MB perf.data (~87572 samples) ] > > With Stephane's patch > > [PATCH] perf: make perf.data more self-descriptive (v8) > > I could extend perf report to add an IBS parser (I need to know the > pmu name/type value mapping). > > Do you have something like that in mind? > > As all these patches are still off-tree I would rather prefer to > decouple the IBS patches from a parser implementation and add it > later as a single patch series. Hmm? Yeah, i'd like to have something that i can try out in practice on an AMD box without having to apply any other patches. The perf.data extension patch from Stephane is now in perf/core. You could add Lin Ming's patch to your tree - they really interdepend. That way it could be reviewed and handled as a coherent unit offering some real, testable functionality. > > - Only root/privileged users should be able to access it. Right now > > i think it's root-only due to percpu restrictions, but wanted to > > mention it that this is an explicit requirement. > > Yes, IBS is restricted to percpu. And percpu requires root > privileges like all other pmu events. What is your point here? My point is that this should not just be an incidental side-effect of hardware limitations but should stay so until deeper integration is achieved. The list i gave is similar for other future PMU additions. Anyway, if perf report [and, in latest perf/core, perf top] can do IBS output that would be a sufficient level of integration i think. Thanks, Ingo -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to majordomo@...r.kernel.org More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
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