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SubjectRe: [PATCH 5/5] perf tools: Enhance parsing events tracepoint error output
On Mon, Sep 07, 2015 at 10:38:07AM +0200, Jiri Olsa wrote:
> Enhancing parsing events tracepoint error output. Adding
> more verbose output when the tracepoint is not found or
> the tracing event path cannot be access.
>
> $ sudo perf record -e sched:sched_krava ls
> event syntax error: 'sched:sched_krava'
> \___ unknown tracepoint
>
> Error: File /sys/kernel/debug/tracing//tracing/events/sched/sched_krava not found.
> Hint: Perhaps this kernel misses some CONFIG_ setting to enable this feature?.
>
> Run 'perf list' for a list of valid events
> ...
>
> $ perf record -e sched:sched_krava ls
> event syntax error: 'sched:sched_krava'
> \___ can't access trace events
>
> Error: No permissions to read /sys/kernel/debug/tracing//tracing/events/sched/sched_krava
> Hint: Try 'sudo mount -o remount,mode=755 /sys/kernel/debug'

What about tracefs? On my system, tracefs is mounted on
/sys/kernel/debug/tracing thus I cannot access trace events after
remounting debugfs with mode=755.

Also, IIRC tracepoint events adds PERF_SAMPLE_RAW bit automatically,
and it requires perf_event_paranoid being -1 for non-root user, right?

Thanks,
Namhyung


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