Re: [PATCH 2/7] perf/cgroup: order events in RB tree by cgroup id

[Ian Rogers]

On Mon, Jul 8, 2019 at 9:16 AM Peter Zijlstra <peterz@xxxxxxxxxxxxx> wrote:
>
> On Mon, Jul 01, 2019 at 11:59:50PM -0700, Ian Rogers wrote:
> > +static int visit_groups_merge(struct perf_event_context *ctx,
> > +                           struct perf_cpu_context *cpuctx,
> > +                           struct perf_event_groups *groups,
> > +                           int (*func)(struct perf_event_context *,
> > +                                       struct perf_cpu_context *,
> > +                                       struct perf_event *,
> > +                                       int *),
> > +                           int *data)
>
> > -struct sched_in_data {
> > -     struct perf_event_context *ctx;
> > -     struct perf_cpu_context *cpuctx;
> > -     int can_add_hw;
> > -};
> > -
> > -static int pinned_sched_in(struct perf_event *event, void *data)
> > +static int pinned_sched_in(struct perf_event_context *ctx,
> > +                        struct perf_cpu_context *cpuctx,
> > +                        struct perf_event *event,
> > +                        int *unused)
> >  {
> > -     struct sched_in_data *sid = data;
> > -
> >       if (event->state <= PERF_EVENT_STATE_OFF)
> >               return 0;
> >
> >       if (!event_filter_match(event))
> >               return 0;
> >
> > -     if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {
> > -             if (!group_sched_in(event, sid->cpuctx, sid->ctx))
> > -                     list_add_tail(&event->active_list, &sid->ctx->pinned_active);
> > +     if (group_can_go_on(event, cpuctx, 1)) {
> > +             if (!group_sched_in(event, cpuctx, ctx))
> > +                     list_add_tail(&event->active_list, &ctx->pinned_active);
> >       }
> >
> >       /*
> > @@ -3317,24 +3444,25 @@ static int pinned_sched_in(struct perf_event *event, void *data)
> >       return 0;
> >  }
> >
> > -static int flexible_sched_in(struct perf_event *event, void *data)
> > +static int flexible_sched_in(struct perf_event_context *ctx,
> > +                          struct perf_cpu_context *cpuctx,
> > +                          struct perf_event *event,
> > +                          int *can_add_hw)
> >  {
> > -     struct sched_in_data *sid = data;
> > -
> >       if (event->state <= PERF_EVENT_STATE_OFF)
> >               return 0;
> >
> >       if (!event_filter_match(event))
> >               return 0;
> >
> > -     if (group_can_go_on(event, sid->cpuctx, sid->can_add_hw)) {
> > -             int ret = group_sched_in(event, sid->cpuctx, sid->ctx);
> > +     if (group_can_go_on(event, cpuctx, *can_add_hw)) {
> > +             int ret = group_sched_in(event, cpuctx, ctx);
> >               if (ret) {
> > -                     sid->can_add_hw = 0;
> > -                     sid->ctx->rotate_necessary = 1;
> > +                     *can_add_hw = 0;
> > +                     ctx->rotate_necessary = 1;
> >                       return 0;
> >               }
> > -             list_add_tail(&event->active_list, &sid->ctx->flexible_active);
> > +             list_add_tail(&event->active_list, &ctx->flexible_active);
> >       }
> >
> >       return 0;
> > @@ -3344,30 +3472,24 @@ static void
> >  ctx_pinned_sched_in(struct perf_event_context *ctx,
> >                   struct perf_cpu_context *cpuctx)
> >  {
> > -     struct sched_in_data sid = {
> > -             .ctx = ctx,
> > -             .cpuctx = cpuctx,
> > -             .can_add_hw = 1,
> > -     };
> > -
> > -     visit_groups_merge(&ctx->pinned_groups,
> > -                        smp_processor_id(),
> > -                        pinned_sched_in, &sid);
> > +     visit_groups_merge(ctx,
> > +                        cpuctx,
> > +                        &ctx->pinned_groups,
> > +                        pinned_sched_in,
> > +                        NULL);
> >  }
> >
> >  static void
> >  ctx_flexible_sched_in(struct perf_event_context *ctx,
> >                     struct perf_cpu_context *cpuctx)
> >  {
> > -     struct sched_in_data sid = {
> > -             .ctx = ctx,
> > -             .cpuctx = cpuctx,
> > -             .can_add_hw = 1,
> > -     };
> > +     int can_add_hw = 1;
> >
> > -     visit_groups_merge(&ctx->flexible_groups,
> > -                        smp_processor_id(),
> > -                        flexible_sched_in, &sid);
> > +     visit_groups_merge(ctx,
> > +                        cpuctx,
> > +                        &ctx->flexible_groups,
> > +                        flexible_sched_in,
> > +                        &can_add_hw);
> >  }
>
> It is not clear to me why you're doing away with that sched_in_data
> abstraction. AFAICT that has no material impact on this patch.

The change alters visit_groups_merge parameters to take ctx and cpuctx
in order to compute the number of iterators. ctx and cpuctx were taken
out of sched_in_data to avoid passing them twice. can_add_hw remains
but not wrapped inside of sched_in_data as it seemed unnecessary to
wrap a single boolean.

Thanks,
Ian