perf: PERF_EVENT_IOC_RESET and multiplexing

* perf: PERF_EVENT_IOC_RESET and multiplexing
@ 2012-08-20 18:53 Vince Weaver
  0 siblings, 0 replies; only message in thread
From: Vince Weaver @ 2012-08-20 18:53 UTC (permalink / raw)
  To: linux-kernel
  Cc: mingo, a.p.zijlstra, Paul Mackerras, Arnaldo Carvalho de Melo,
	Stephane Eranian

Hello

I have a perf API question.

When I run PERF_EVENT_IOC_RESET, all it resets is the event count.
It does not reset the PERF_FORMAT_TOTAL_TIME_ENABLED or
PERF_FORMAT_TOTAL_TIME_RUNNING values.

Is this expected?  It means if I'm trying to do multiplexing and want to 
reset the counts to zero, there's no way to reset the enabled/running 
values.

I suppose I can just close/reopen the events, or allocate some space to 
store the previous values, but that seems like unncessary overhead.

As an aside while I have your attention, can someone explain the 
difference between the "inherit" and the "inherit_stat" options in
perf.attr?  I can't seem to make a test case exhibit a difference, and
the events/core.c code in the kernel is a horrible wall of uncommented 
code that is nearly impossible to follow.

Thanks,

Vince
vweaver1@eecs.utk.edu

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