Re: Reading perf counters at ftrace trace boundaries

Andi Kleen
2013-08-12T01:23:12Z

Karim Yaghmour <karim.yaghmour@opersys.com> writes:

> Wondering if there's a way for reading perf counters in the kernel. I'd
> like to read/record perf counters on ftrace function tracing
> entries/exits to provide a rundown of the value of various counters on
> function call boundaries.

KVM does it, see arch/x86/kvm/pmu.c. Essentially it would be doing RDPMC.

But the overhead will be likely very high, some sampling approach
is likely better.

-Andi

--
ak@linux.intel.com -- Speaking for myself only