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    SubjectRe: perf: record segfaults for cycles event when collecting data on a VM
    On Wed, Feb 08, 2012 at 10:53:04AM -0700, David Ahern wrote:

    > The segfault is in the event processing once the collection is done
    > (perf-record), so the time length should not matter.

    Yes, but I wanted to make sure there is a GUEST_KERNEL sample in there
    to process. It usually takes some time (at least in my tests) to get a
    spurious one.

    > Either way, this fixes the segafult:
    >
    > diff --git a/tools/perf/util/util.c b/tools/perf/util/util.c
    > index 8131410..fb25d13 100644
    > --- a/tools/perf/util/util.c
    > +++ b/tools/perf/util/util.c
    > @@ -6,7 +6,7 @@
    > * XXX We need to find a better place for these things...
    > */
    > bool perf_host = true;
    > -bool perf_guest = true;
    > +bool perf_guest = false;
    >
    > void event_attr_init(struct perf_event_attr *attr)
    > {
    >
    > which makes sense. It forces perf_session__find_machine_for_cpumode() to
    > return the host machine always.

    Great, thanks. I will send two patches tomorrow to fix Jason's problem
    and change the default for perf_guest.


    Joerg

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    AMD Operating System Research Center

    Advanced Micro Devices GmbH Einsteinring 24 85609 Dornach
    General Managers: Alberto Bozzo
    Registration: Dornach, Landkr. Muenchen; Registerger. Muenchen, HRB Nr. 43632



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