Messages in this thread | | | Date | Fri, 24 Jun 2011 02:11:48 +0200 | From | Frederic Weisbecker <> | Subject | Re: Using a new perf tool against an older kernel |
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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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