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SubjectRe: [PATCH] perf tools pt: Remove obsolete paragraph in intel-pt.c
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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