Re: [PATCH 0/5] perf/mm: Fix PERF_SAMPLE_*_PAGE_SIZE

[Peter Zijlstra]

On Mon, Nov 16, 2020 at 08:36:36AM -0800, Dave Hansen wrote:
> On 11/16/20 8:32 AM, Matthew Wilcox wrote:
> >>
> >> That's really the best we can do from software without digging into
> >> microarchitecture-specific events.
> > I mean this is perf.  Digging into microarch specific events is what it
> > does ;-)
> 
> Yeah, totally.

Sure, but the automatic promotion/demotion of TLB sizes is not visible
if you don't know what you startd out with.

> But, if we see a bunch of 4k TLB hit events, it's still handy to know
> that those 4k TLB hits originated from a 2M page table entry.  This
> series just makes sure that perf has the data about the page table
> mapping sizes regardless of what the microarchitecture does with it.

This.