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SubjectRe: [PATCH] perf record: Change error message on failure

* Robert Richter <robert.richter@amd.com> wrote:

> On 13.09.12 17:07:20, Ingo Molnar wrote:
> >
> > * Robert Richter <robert.richter@amd.com> wrote:
> >
> > > Only report
> > >
> > > No CONFIG_PERF_EVENTS=y kernel support configured?
> > >
> > > if the syscall fails with ENOSYS. In other cases CONFIG_PERF_EVENTS is
> > > set and might confuse users. The default message is now:
> > >
> > > Not all events could be opened.
> >
> > Indeed, and it would be nice to be even less passive-aggressive
> > and figure out and display the exact error condition?
>
> The complete error message shows the error condition and is like the
> following:
>
> # perf record -e cycles:ppk sleep 1
>
> Error: sys_perf_event_open() syscall returned with 22 (Invalid argument). /bin/dmesg may provide additional information.
>
> Not all events could be opened.
> sleep: Terminated

So in this case a better message would be something like:

Error: sys_perf_event_open() syscall failed because the 'cycles:ppk' event could not be opened
sleep: Terminated

The user is not interested in the dmesg details, nor in that the
error code is 22 -EINVAL.

Thanks,

Ingo


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