Re: [V3][PATCH 0/7] perf, x86: Implement AMD IBS

From: Robert Richter
Date: Tue Oct 04 2011 - 10:27:03 EST

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 (~87572 samples) ]

With Stephane's patch

[PATCH] perf: make 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?

> - 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?


Advanced Micro Devices, Inc.
Operating System Research Center

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