Re: [PATCH V3 0/5] bugs fix for large PEBS mmap read and rdpmc read

[Liang, Kan]

On 1/31/2018 8:15 AM, Jiri Olsa wrote:
> On Wed, Jan 31, 2018 at 10:15:39AM +0100, Jiri Olsa wrote:
> > On Tue, Jan 30, 2018 at 07:59:41PM -0800, Andi Kleen wrote:
> > > > Still, the part I am missing here, is why asking for
> > > > PERF_SAMPLE_PERIOD voids large PEBS.
> > >
> > > I think it was disabled together with frequency mode
> > > (which we could support too, but it's a bit more work)
> > >
> > > But yes PERIOD could probably be allowed.
> >
> > looks like it's just a matter of adding PERF_SAMPLE_PERIOD
> > into PEBS_FREERUNNING_FLAGS, we already populate period
> > in setup_pebs_sample_data
> >
> > jirka
> >
> >
> > ---
> > diff --git a/arch/x86/events/perf_event.h b/arch/x86/events/perf_event.h
> > index 8e4ea143ed96..78f91ec1056e 100644
> > --- a/arch/x86/events/perf_event.h
> > +++ b/arch/x86/events/perf_event.h
> > @@ -93,7 +93,8 @@ struct amd_nb {
> >   	PERF_SAMPLE_ID | PERF_SAMPLE_CPU | PERF_SAMPLE_STREAM_ID | \
> >   	PERF_SAMPLE_DATA_SRC | PERF_SAMPLE_IDENTIFIER | \
> >   	PERF_SAMPLE_TRANSACTION | PERF_SAMPLE_PHYS_ADDR | \
> > -	PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER)
> > +	PERF_SAMPLE_REGS_INTR | PERF_SAMPLE_REGS_USER | \
> > +	PERF_SAMPLE_PERIOD)
>
> seems to work, getting large PEBS event for following command line:
>
>    perf record -e cycles:P -c 100 --no-timestamp -C 0 --period

Yes, I tried the patch. The large PEBS can be enabled with the PERIOD 
flag. Everything looks good.

Jirka, could you please post the patch as well?

Thanks,
Kan