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    SubjectRe: Using a new perf tool against an older kernel
    On Thu, Jun 23, 2011 at 02:02:15PM -0600, David Ahern wrote:
    >
    >
    > On 06/23/2011 01:39 PM, Arun Sharma wrote:
    > > On 6/23/11 7:22 AM, David Ahern wrote:
    > >
    > >> I have not seen issues like this using newer perf userspace against
    > >> older kernels. For example, my laptop was running Fedora 14 (2.6.35) and
    > >> now Fedora 15 (2.6.38.8) and I typically use latest perf builds (e.g.,
    > >> testing patches).
    > >
    > > I narrowed it down to PERF_SAMPLE_RAW:
    > >
    > > perf record -ag -- sleep 1
    > >
    > > is fine, but:
    > >
    > > perf record -agR -- sleep 1
    > >
    > > fails for me most of the time. The reason I needed to use the -R in the
    > > first place is that "perf script" fails on older kernels with:
    > >
    > > Samples do not contain timestamps.
    > >
    > > With the newer perf, I don't get errors, but the timestamp field is
    > > invalid. So I need to use the -R flag to get valid timestamps +
    > > stacktraces out of "perf script".
    >
    > That should have been fixed.
    >
    > And -T on record gets the timestamps.
    >
    > David

    Right, it would be nice to suggest that from perf script when timestamps
    are not recorded.


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