Re: Reading perf counters at ftrace trace boundaries

Karim Yaghmour
2013-08-12T01:39:11Z

On 13-08-11 10:23 PM, Andi Kleen wrote:
> KVM does it, see arch/x86/kvm/pmu.c. Essentially it would be doing RDPMC.

Thx for the pointer, appreciated.

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

Indeed. It doesn't actually have to be at every single ftrace
begin/exit. But possibly starting with some kind of every nth and then
drilling down as the culprit is incrementally singled-out.