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
--
To unsubscribe from this list: send the line "unsubscribe linux-kernel" in
the body of a message to majordomo@xxxxxxxxxxxxxxx
More majordomo info at http://vger.kernel.org/majordomo-info.html
Please read the FAQ at http://www.tux.org/lkml/