Re: [PATCH V6 03/16] perf/core: Add support for PERF_SAMPLE_CODE_PAGE_SIZE

[Liang, Kan]

On 8/10/2020 5:41 PM, Peter Zijlstra wrote:
> On Mon, Aug 10, 2020 at 02:24:23PM -0700, Kan Liang wrote:
> > From: Stephane Eranian <eranian@xxxxxxxxxx>
> >
> > When studying code layout, it is useful to capture the page size of the
> > sampled code address.
> >
> > Add a new sample type for code page size.
> > The new sample type requires collecting the ip. The code page size can
> > be calculated from the IRQ-safe perf_get_page_size().
> >
> > Only the generic support is covered. The large PEBS will be disabled
> > with this sample type.
>
> -ENOREASON

I think the reason is similar to PERF_SAMPLE_DATA_PAGE_SIZE. For large 
PEBS, the mapping could be gone for the earlier PEBS records. Invalid 
page size may be retrieved. I will update the commit message.

Thanks,
Kan