Re: perf: PERF_EVENT_IOC_PERIOD on ARM vs everywhere else

From: Will Deacon
Date: Mon Oct 28 2013 - 08:54:39 EST

On Mon, Oct 28, 2013 at 10:00:49AM +0000, Peter Zijlstra wrote:
> On Mon, Oct 28, 2013 at 08:57:00AM +0000, Will Deacon wrote:
> > > Should other architectures be updated to? I just wanted to find out the
> > > rationale for this before I update the manpage to reflect the difference
> > > in behaviors between architectures.
> >
> > I don't want to be the `oddball' architecture (at least, not more than I am
> > already :), but I do find it tricky to follow the required semantics of perf
> > as opposed to `it happens to work this way', especially when so much of it
> > is buried in the various arch backends. So if somebody using the thing on
> > ARM has (what looks to me like) a valid issue, then I usually try and fix
> > it.
> Hurmph.. at least raise the issue for the other archs.

Yeah, sorry about that. I thought Stephane might take it forward (since he
was on the perfmon thread I linked to) and I did CC you on the patch.

While we're at it, there was another patch that I CC'd others on since it
might be wanted by other architectures too: cb2d8b342aa0 ("ARM: 7698/1:
perf: fix group validation when using enable_on_exec"). Basically, the
patch ensures that events that are set to enable on exec are included in
group validation, despite being in the OFF state at validation time.

Any thoughts on that?

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