Re: Reading perf counters at ftrace trace boundaries

[Karim Yaghmour]

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.

-- 
Karim Yaghmour
CEO - Opersys inc. / www.opersys.com
http://twitter.com/karimyaghmour

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