Re: [RFC][PATCH 00/11] perf pmu interface -v2

MattFleming
2010-07-01T15:31:15Z

On Thu, Jul 01, 2010 at 05:02:35PM +0200, Peter Zijlstra wrote:
>
> Matt, you said it broke SH completely, but did you try perf stat? perf
> record is not supposed to work on SH due to the hardware not having an
> overflow interrupt.

perf record does work to some degree. It definitely worked before
applying your changes but not after. I admit I haven't really read the
perf event code, but Paul will know.

> Which made me think, what on SH guarantees we update the counter often
> enough not to suffer from counter wrap? Would it make sense to make the
> SH code hook into their arch tick handler and update the counters from
> there?

This was the way that the oprofile code used to work. Paul and I were
talking about using a hrtimer to sample performance counters as
opposed to piggy-backing on the tick handler.