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    SubjectRe: [BUG(?)] perf_events: combining multiple tracepoint events into a group produces no counts on member events
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    On Tue, 2010-11-30 at 17:00 -0800, Corey Ashford wrote:
    > Hi,
    >
    > I'm not sure that what I'm seeing is a bug, or was something intentional.
    >
    > If I place multiple tracepoint events into a group and measure counts of
    > these events on a process, I get no counts for the tracepoint events
    > other than the group leader.
    >
    > Is this expected behavior?
    >
    > It's not clear to me why this should be the case; grouping shouldn't
    > have any ill effects on tracepoint events, from my understanding.
    >
    > I noticed this because my private version of the perf tool has the event
    > group patch https://lkml.org/lkml/2010/11/24/584 as well as the patch
    > which fixes the parsing of multiple tracepoint events in the same -e
    > switch: https://lkml.org/lkml/2010/11/30/460
    >
    > When I dig into the code a bit, I find that each event opens
    > successfully, so that's not the problem. If I disable the grouping,
    > then I get counts for all of the tracepoint events.

    Hrm,.. definitely not expected. I'll try and look into it, but I'm a bit
    over-committed atm.

    Also, I've started a rewrite of the whole tracepoint <-> perf
    interaction:

    http://lkml.org/lkml/2010/11/23/147

    Could you see if that cures your problem?

    Another thing to test, does the same hold true for regular software
    events? tracepoints and software events share a lot of infrastructure.




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