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[Bug translator/13820] timer.profile(NNN) variant using perf probes


http://sourceware.org/bugzilla/show_bug.cgi?id=13820

--- Comment #1 from Frank Ch. Eigler <fche at redhat dot com> 2012-03-08 01:48:28 UTC ---
e.g.

  probe timer.profile.hz(997) { }

could map on a 2000 MHz core to perf.hw.cpu_clock

  probe perf.type(0).config(0).sample(2006018) { }

(where 2006018 would be 2,000,000,000 / 997).
This would have to be calculated at module startup time.
And it may be that we'd actually need a more complicated
function, or even some sort of baby PLL, to approximate
the desired frequency.

It would probably be unwise to map timer.{hz,ms,etc.}(NNN)
to this because this uses up scarce resources, so can't be
unprivileged-safe.

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