Re: [PATCH v3 04/10] perf: Add per perf_cpu_context min_heap storage

[Ian Rogers]

On Thu, Nov 14, 2019 at 1:51 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Wed, Nov 13, 2019 at 04:30:36PM -0800, Ian Rogers wrote:
> > +     if (cpuctx) {
> > +             event_heap = (struct min_max_heap){
> > +                     .data = cpuctx->itr_storage,
> > +                     .size = 0,
>
> C guarantees that unnamed fields get to be 0

Agreed, this is kept here to aid readability. Do you feel strongly
about not having this? It appears to be kept elsewhere for clarity
too:
$ grep -r "\..*= 0," arch/ kernel/ tools/|wc -l
2528

> > +                     .cap = cpuctx->itr_storage_cap,
> > +             };
> > +     } else {
> > +             event_heap = (struct min_max_heap){
> > +                     .data = itrs,
> > +                     .size = 0,
>
> idem.
>
> > +                     .cap = ARRAY_SIZE(itrs),
> > +             };
> > +             /* Events not within a CPU context may be on any CPU. */
> > +             __heap_add(&event_heap, perf_event_groups_first(groups, -1));
> > +
>
> suprious whitespace

Done.



> > +     }
> > +     evt = event_heap.data;
> > +
> >       __heap_add(&event_heap, perf_event_groups_first(groups, cpu));