Re: [RFC][PATCH 09/11] perf: Default PMU ops

Peter Zijlstra
2010-06-29T16:34:27Z

On Tue, 2010-06-29 at 17:03 +0200, Frederic Weisbecker wrote:
> > You mean, if (!pmu->start_txn && pmu->pmu_enable) { /* install defaults
> > */ } ?
>
>
> Not really. pmu_*able and txn are there for different purposes.
> A pmu implementation may want to provide enable/disable things
> but not require any txn. Or one may just not need any of those,
> like software events.
>
> It should simply map to a nop if nothing is provided.

Thing is, using at least the pmu_enable/disable fallback when no txn
methods are provided can save bunch of hardware writes. So this trivial
fallback makes sense.