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    SubjectRe: pref record question
    On Tue, 2009-10-20 at 08:00 +0200, Ingo Molnar wrote:
    > * Peter Zijlstra <> wrote:
    > > On Mon, 2009-10-19 at 19:04 +0200, Tim Blechmann wrote:
    > >
    > > > i am trying to do some profiling with perf ( while
    > > > thread-level profiling works fine, i haven't been able to record
    > > > profiling data of a whole process (i.e. main thread + child
    > > > threads). from my understanding, this should be enabled by running
    > > > 'perf record -i' on the main thread. this does only collect the data
    > > > from the main thread, though.
    > > >
    > > > is this an issue with perf or with my understanding of perf?
    > >
    > > -i will only inherit the counters on new fork()/clone() calls, so an
    > > existing process/task tree will not automagically get the counters.
    > Looks like something very much worth fixing.

    Well, maybe.

    There's two ways to go about this, either iterate the tasks in userspace
    and attach a counter to each one (repeat until there's no new ones

    Or add a new flag in perf_event_attr to iterate the tasks on attach in
    an atomic manner.

    We cannot simply extend the current attach behaviour as that would make
    it impossible to attach to a single thread in a thread group.

    Also, if you extend the interface, it would make sense to allow
    automatically attaching to a process group, not only a thread group,

     \ /
      Last update: 2009-10-20 11:23    [W:0.020 / U:5.868 seconds]
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