Re: register_timer_hook use in arch/sh/oprofile

Ingo Molnar
2009-06-26T07:24:15Z

* 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.

> But for proper 64 bit hardware counters there is indeed no need
> for that.

Indeed - although they are rare.

Ingo