Re: [tip:perfcounters/core] perf_counter: x86: Fix call-chain support to use NMI-safe methods

Ingo Molnar
2009-06-15T18:47:55Z

* Mathieu Desnoyers <mathieu.desnoyers@polymtl.ca> wrote:

> > If it's a slowdown then the decision is easy: we dont want this,
> > we want to push the overhead into the sampling code, away from
> > common codepaths.
>
> I did not try to make the "hand unroll + ret" the default. I
> therefore don't know if it is faster or slower than iret. But I
> prefered to stay on the safe side and only modify the exceptions
> nested within NMI handlers.

hm, i misread that bit then. Too bad.

Btw., that speedup question is still valid. (Just not relevant here
and now.)

Ingo