On Mon, Aug 10, 2020 at 06:37:08PM -0400, Liang, Kan wrote: > > > 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 <[email protected]> > > > > > > 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.
That's extremely unlikely though.. We might as well just do it and pray. The worst case is that we return '0' page-size because it's gone, that seems fairly sane. Alternatively, we can register mmu_notifiers or something and flush PEBS buffers when ranges get invalidated.
