Re: [PATCH 2/7] Simple Performance Counters: x86_64 support

Christoph Lameter
2007-08-01T18:45:50Z

On Wed, 1 Aug 2007, Andi Kleen wrote:

> > It is certainly interesting to compare alternative ways of handling the
> > instruction streams by various processors or models of processors.
>
> Well you have to do a lot more work then to handle instable TSCs then.

I have been using this for 2 years. It works fine for my purposes.

> In particular the frequencies can be different between CPUs, they
> change (which you can catch with cpufreq notifiers) and during the
> cpufreq change period they're instable (as in you can't tell for
> some time which frequency they're currently running at and they
> might be running immediate frequencies)

Well then simply make sure that they do not change while you measure.