Messages in this thread | | | Date | Mon, 2 Sep 2013 09:15:48 -0400 (EDT) | From | Vince Weaver <> | Subject | Re: perf_event: rdpmc self-monitoring overhead issue |
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On Mon, 2 Sep 2013, Stephane Eranian wrote:
> On Mon, Sep 2, 2013 at 4:50 AM, Andi Kleen <andi@firstfloor.org> wrote: > > Stephane Eranian <eranian@googlemail.com> writes: > > > >> I don't see a flag in mmap() to fault it in immediately. > > > > MAP_PRESENT > > > I could not find this constant defined anywhere in the kernel source tree > nor in /usr/include. Are you sure of the name?
I assume he means MAP_POPULATE
which does improve things, from ~3000 cycles to ~219 cycles but that's still more overhead than the ~130 or so you get by manually touching the page first.
Vince
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