perf: is PERF_COUNT_SW_CONTEXT_SWITCHES a kernel or user event?
From: Vince Weaver
Date: Fri Jun 24 2011 - 17:03:53 EST
Hello
the commit included in 2.6.34:
perf: Use hot regs with software sched switch/migrate events
e49a5bd38159dfb1928fd25b173bc9de4bbadb21
Changes the behavior of the PERF_COUNT_SW_CONTEXT_SWITCHES
counter.
Before 2.6.34 all of the PERF_COUNT_SW_CONTEXT_SWITCHES events were
counted as happening in userspace (they show up in "perf stat -e cs:u")
but after the commit they always happen in kernelspace ("perf stat -e
cs:k").
Was this intended behavior?
I'm writing a validation test for this and want to make sure I get it
right.
This can be confusing if your tool defaults to userspace only counts (PAPI
does this).
Thanks,
Vince
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