lkml.org 
[lkml]   [2009]   [Oct]   [20]   [last100]   RSS Feed
Views: [wrap][no wrap]   [headers]  [forward] 
 
Messages in this thread
    /
    SubjectRe: pref record question
    From
    Date
    On Tue, 2009-10-20 at 08:00 +0200, Ingo Molnar wrote:
    > * Peter Zijlstra <peterz@infradead.org> wrote:
    >
    > > On Mon, 2009-10-19 at 19:04 +0200, Tim Blechmann wrote:
    > >
    > > > i am trying to do some profiling with perf (2.6.31.4). 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
    left).

    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,
    etc.





    \
     
     \ /
      Last update: 2009-10-20 11:23    [W:0.022 / U:359.008 seconds]
    ©2003-2016 Jasper Spaans. hosted at Digital OceanAdvertise on this site