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

Ingo Molnar
2009-06-15T19:08:54Z

* Ingo Molnar <mingo@elte.hu> wrote:

> > To a point where it cannot afford a simple register save/restore
> > ?
> >
> > There is "caring" and "_caring_". I am tempted to ask what NMI
> > handler execution frequency you have in mind here to figure out
> > if we are not trying to optimize sub-nanoseconds per minutes. ;)
>
> I routinely run 'perf' with half a million NMIs per second or
> more. ( Why wait 10 seconds for a profile you can get in 1 second?
> ;-)
>
> Granted that is over multiple CPUs - but still performance does
> matter here too.
>
> Reading cr2 is certainly fast. Writing it - dunno.

But one thing is sure: it is certainly going to be faster than the
INVLPG(s!) we have to do with the GUP solution.

Ingo