Re: [PATCH v7 01/15] sched/core: uclamp: Add CPU's clamp buckets refcounting

Peter Zijlstra
2019-03-13T19:48:38Z

On Wed, Mar 13, 2019 at 04:12:29PM +0000, Patrick Bellasi wrote:
> On 13-Mar 14:40, Peter Zijlstra wrote:
> > On Fri, Feb 08, 2019 at 10:05:40AM +0000, Patrick Bellasi wrote:
> > > +static inline unsigned int uclamp_bucket_id(unsigned int clamp_value)
> > > +{
> > > + return clamp_value / UCLAMP_BUCKET_DELTA;
> > > +}
> > > +
> > > +static inline unsigned int uclamp_bucket_value(unsigned int clamp_value)
> > > +{
> > > + return UCLAMP_BUCKET_DELTA * uclamp_bucket_id(clamp_value);
> >
> > return clamp_value - (clamp_value % UCLAMP_BUCKET_DELTA);
> >
> > might generate better code; just a single division, instead of a div and
> > mult.
>
> Wondering if compilers cannot do these optimizations... but yes, looks
> cool and will do it in v8, thanks.

I'd be most impressed if they pull this off. Check the generated code
and see I suppose :-)