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    SubjectRe: [RFC PATCH 3/3 v2] perf: Update perf tool to monitor uncore events
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    On Sun, 2010-11-21 at 20:22 +0800, Stephane Eranian wrote:
    > On Sun, Nov 21, 2010 at 1:09 PM, Andi Kleen <andi@firstfloor.org> wrote:
    > >
    > >>
    > >> samples pcnt function DSO
    > >> _______ _____ ______________________
    > >> ____________________________________
    > >>
    > >> 8.00 18.6% kallsyms_expand_symbol [kernel.kallsyms]
    > >
    > > Reporting a symbol for an uncore event seems highly misleading.
    > > After all the uncore counter has no idea for which core the event was,
    > > so there isn't really any instruction pointer to report.
    > > The event could be event caused by a PCI device or similar.
    > >
    > > For per function monitoring of uncore events one has to use
    > > OFFCORE_RESPONSE, like I implemented recently.
    > >
    > > I would suggest to not report any symbol names for uncore events.
    > > Doing so just will confuse users.
    > >
    > > In fact I suspect uncore events are only really useful
    > > with "stat", but not with "top", or if they are used in top
    > > then the symbol reporting should be disabled.
    > >
    > I agree, uncore should only be used for counting on a
    > per-cpu basis. You can leave the perf tool as is, but
    > that opens up the risk of misinterpretation by many users,
    > or you restrict this in the tool directly which is the better
    > solution in my mind.

    I agree restricting the tool is a better idea.
    How about below?

    #one cpu stat is allowed
    perf stat -e ruNNNN -C <cpu>
    perf stat -e ruNNNN -C <cpu> -p <pid>
    perf stat -e ruNNNN -C <cpu> -- <command>

    #per thread is NOT allowed
    perf stat -e ruNNNN -p <pid>
    perf stat -e ruNNNN -- <command>

    #all cpus stat is NOT allowed, because it will mess the results
    perf stat -e ruNNNN -a








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