Re: register_timer_hook use in arch/sh/oprofile

Peter Zijlstra
2009-06-26T07:36:32Z

On Fri, 2009-06-26 at 09:23 +0200, Ingo Molnar wrote:
> * Peter Zijlstra <peterz@infradead.org> wrote:
>
> > On Wed, 2009-06-24 at 15:24 +0200, Ingo Molnar wrote:
> > >
> > > [ And long-term analysis ('perf stat' type of runs) dont need IRQs
> > > anyway - perfcounters reads outs the counts and summarizes them
> > > across the measured workload. ]
> >
> > If the counter width is less than 64 bits we do need to have some
> > interrupt to read them from before they cycle so we can accumulate
> > the deltas into a proper u64.
>
> Yeah - but even that can be driven from some housekeeping hrtimer.

Oh absolutely, but its one of those things one should not forget to do.

> > But for proper 64 bit hardware counters there is indeed no need
> > for that.
>
> Indeed - although they are rare.

Paul Mundt mentioned he had some.