Messages in this thread | | | Date | Wed, 9 Nov 2016 10:14:26 -0300 | From | Arnaldo Carvalho de Melo <> | Subject | Re: [PATCH] perf tools pt: Remove obsolete paragraph in intel-pt.c |
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Em Tue, Nov 08, 2016 at 04:11:00PM -0800, Andi Kleen escreveu: > From: Andi Kleen <ak@linux.intel.com> > > Since the unprivileged sched switch event was added in perf, > PT doesn't need need perf_event_paranoid=-1 anymore for > per cpu decoding. So remove the obsolete paragraph in > the documentation.
Thanks for pointing that out, I'll do something slightly different tho, pointing out that from kernel X.Y.Z, when the unprivileged PERF_RECORD_SWITCH metadata event was introduced, this is no longer an issue, having to be considered only on older kernels.
- Arnaldo
> Cc: adrian.hunter@intel.com > Signed-off-by: Andi Kleen <ak@linux.intel.com> > --- > tools/perf/Documentation/intel-pt.txt | 10 ---------- > 1 file changed, 10 deletions(-) > > diff --git a/tools/perf/Documentation/intel-pt.txt b/tools/perf/Documentation/intel-pt.txt > index c6c8318e38a2..c7f817fd3611 100644 > --- a/tools/perf/Documentation/intel-pt.txt > +++ b/tools/perf/Documentation/intel-pt.txt > @@ -550,16 +550,6 @@ Unless /proc/sys/kernel/perf_event_paranoid is set to -1, unprivileged users > have memory limits imposed upon them. That affects what buffer sizes they can > have as outlined above. > > -Unless /proc/sys/kernel/perf_event_paranoid is set to -1, unprivileged users are > -not permitted to use tracepoints which means there is insufficient side-band > -information to decode Intel PT in per-cpu mode, and potentially workload-only > -mode too if the workload creates new processes. > - > -Note also, that to use tracepoints, read-access to debugfs is required. So if > -debugfs is not mounted or the user does not have read-access, it will again not > -be possible to decode Intel PT in per-cpu mode. > - > - > sched_switch tracepoint > ----------------------- > > -- > 2.5.5
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