Use case for PERF_COUNT_HW_REF_CPU_CYCLES generic PMU event

From: Anshuman Khandual
Date: Wed Feb 08 2012 - 04:44:06 EST


Hello Stephane,

I was going through the following discussion where we added the
new HW generic event PERF_COUNT_HW_REF_CPU_CYCLES.

https://lkml.org/lkml/2011/12/10/103

(Sorry, for asking this question bit late)

I am trying to understand the use case for this. Would this new event
help us in generating (during a perf session) a CPU frequency invariant
time metric against which we would plot our other perf event's measurements ?
CPU frequency independent time measurement is it's primary purpose ? or we were
finding a way to expose the fixed counter 2 which was not getting used before
for not having an event encoding. I guess this would help us in finding equivalent
PMU events or mechanisms in other architecture / platforms.

--
Anshuman Khandual
Linux Technology Centre
IBM Systems and Technology Group

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