Re: [PATCH v2] perf/core: Add a new read format to get a number of lost samples

Namhyung Kim
2021-09-10T22:41:03Z

On Fri, Sep 10, 2021 at 2:42 PM Jiri Olsa <jolsa@redhat.com> wrote:
>
> On Wed, Sep 08, 2021 at 10:24:20AM -0700, Namhyung Kim wrote:
> > Sometimes we want to know an accurate number of samples even if it's
> > lost. Currenlty PERF_RECORD_LOST is generated for a ring-buffer which
> > might be shared with other events. So it's hard to know per-event
> > lost count.
> >
> > Add event->lost_samples field and PERF_FORMAT_LOST to retrieve it from
> > userspace.
>
> hi,
> looks good.. will there be some tools/perf change using this?

Sure, I'll work on the userspace part after this is merged.
I'm thinking about adding LOST_SAMPLES records at the end
of the data section as if they came from the kernel.

Thanks,
Namhyung