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SubjectRe: [PATCH 4/5] perf record: mmap output file - v5

* Peter Zijlstra <peterz@infradead.org> wrote:

> On Tue, Nov 19, 2013 at 12:48:10PM +0100, Peter Zijlstra wrote:
> > And that does indeed seem to side-step the perf sw pagefault event, but
> > that is arguably a perf bug.
>
> To clarify; mm/memory.c:handle_mm_fault() is where the VM counts its
> generic PGFAULT event, but our perf sw event is in the arch fault
> handler.
>
> So they count different but related things.

I think that assymetry was intended: we didn't want to count
'synchronous' pagefaults like get_user_pages() or mlock() bringing in
pages, only asynchronous/real ones, or so.

Thanks,

Ingo


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