Re: [patch/rfc] perf on raspberry-pi without overflow interrupt

From: Vince Weaver
Date: Thu Jan 16 2014 - 12:12:12 EST

On Tue, 14 Jan 2014, Peter Zijlstra wrote:

> On Mon, Jan 13, 2014 at 11:55:17PM -0500, Vince Weaver wrote:

> > I don't see an existing pmu capabilities struct... or do you mean
> > coming up with one?
> Yeah, adding one.

So would it be a struct, or just an integer with flags?

> > Would it only hold an "overflow_interrupt_available" flag, or are
> > there other generic capabilities it would be handy to know about?
> Possible (other) flags could be:
> PMU_HAS_INT -- would allow sampling events
> PMU_HAS_PRECISE -- would allow any ::precise value
> PMU_HAS_FILTER -- would allow all os/user/etc. flags

should we export these to userspace somehow?

It would be handy to be able to tell you're getting EOPNOTSUP because
PMU_HAS_INT is not set for your pmu, rather than trying to guess why
things are failing.

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