Re: [V2 PATCH] perf parse-events: Specially handle uncore event alias in small groups

[Liang, Kan]

On 4/25/2018 10:23 AM, Jiri Olsa wrote:
> On Wed, Apr 25, 2018 at 06:50:18AM -0700, kan.liang@xxxxxxxxxxxxxxx wrote:
> > From: Kan Liang <kan.liang@xxxxxxxxxxxxxxx>
> >
> > Perf stat doesn't count the uncore event aliases from the same uncore
> > block in a group, for example:
> >
> >    perf stat -e '{unc_m_cas_count.all,unc_m_clockticks}' -a -I 1000
> >    #           time             counts unit events
> >         1.000447342      <not counted>      unc_m_cas_count.all
> >         1.000447342      <not counted>      unc_m_clockticks
> >         2.000740654      <not counted>      unc_m_cas_count.all
> >         2.000740654      <not counted>      unc_m_clockticks
> >
> > The output is very misleading. It gives a wrong impression that the
> > uncore event doesn't work.
> >
> > An uncore block could be composed by several PMUs. An uncore event alias
> > is a joint name which means the same event runs on all PMUs of a block.
> > Perf doesn't support mixed events from different PMUs in the same group.
> > It is wrong to put uncore event aliases in a big group.
> >
> > The right way is to split the big group into multiple small groups which
> > only include the events from the same PMU.
> > Only uncore event aliases from the same uncore block should be specially
> > handled here. It doesn't make sense to mix the uncore events with other
> > uncore events from different blocks or even core events in a group.
> >
> > With the patch:
> >    #           time             counts unit events
> >       1.001557653            140,833      unc_m_cas_count.all
> >       1.001557653      1,330,231,332      unc_m_clockticks
> >       2.002709483             85,007      unc_m_cas_count.all
> >       2.002709483      1,429,494,563      unc_m_clockticks
>
> hum, I still can see the original behaviour even with the patch:

That's because the data_reads and clockticks are from different uncore 
blocks. The data_reads is a IMC event. The clockticks is a CBOX event.

The patch only supports the events from the same uncore blocks in group.

Thanks,
Kan


> [jolsa@krava perf]$ sudo ./perf stat -e '{data_reads,clockticks}' -a -I 1000
> #           time             counts unit events
>       1.000184929      <not counted> MiB  data_reads
>       1.000184929    <not supported>      clockticks
>       2.000552765      <not counted> MiB  data_reads
>       2.000552765    <not supported>      clockticks
>       3.000846298      <not counted> MiB  data_reads
>       3.000846298    <not supported>      clockticks
>       4.001044852      <not counted> MiB  data_reads
>       4.001044852    <not supported>      clockticks
>       5.001247131      <not counted> MiB  data_reads
>       5.001247131    <not supported>      clockticks
> ^C     5.546917060      <not counted> MiB  data_reads
>       5.546917060    <not supported>      clockticks
>
>
> jirka