Messages in this thread |  | | | Date | Wed, 24 Jun 2009 14:47:55 +0200 | | From | Ingo Molnar <> | | Subject | Re: register_timer_hook use in arch/sh/oprofile |
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* Paul Mackerras <paulus@samba.org> wrote:
> Paul Mundt writes: > > > Yes, that all works fine. My comment was more in reference to > > the hardware performance counters that don't have IRQs of their > > own, which still need to be tied in to the perf_counter API. > > For them you would need to check in hw_perf_counter_init() that > counter->attr.sample_period is zero, and fail with an -EINVAL > error if it isn't.
That would make 'perf stat' work - but 'perf top' and 'perf record' would not.
But those can be made to work as well without hw IRQ support, if the period is simply fed into a special hrtimer, with nanosecs units. The resulting sampling wont be "constant period" - but none of the tools really mind about that.
Ingo
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