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SubjectRe: [PATCH v7 1/2] perf/core: use rb trees for pinned/flexible groups
Date
Alexey Budankov <alexey.budankov@linux.intel.com> writes:

> @@ -3091,61 +3231,55 @@ static void cpu_ctx_sched_out(struct perf_cpu_context *cpuctx,
> }
>
> static void
> -ctx_pinned_sched_in(struct perf_event_context *ctx,
> - struct perf_cpu_context *cpuctx)
> +ctx_pinned_sched_in(struct perf_event *event,
> + struct perf_cpu_context *cpuctx,
> + struct perf_event_context *ctx)

If you're doing this, you also need to rename the function, because it
now schedules in one event and not a context. But better just keep it as
is.

> {
> - struct perf_event *event;
> -
> - list_for_each_entry(event, &ctx->pinned_groups, group_entry) {

Why not put your new iterator here in place of the old one, instead of
moving things around? Because what follows is hard to read and is also
completely unnecessary:

> - if (event->state <= PERF_EVENT_STATE_OFF)
> - continue;
> - if (!event_filter_match(event))
> - continue;
> + if (event->state <= PERF_EVENT_STATE_OFF)
> + return;
> + if (!event_filter_match(event))
> + return;

like this,

>
> - /* may need to reset tstamp_enabled */
> - if (is_cgroup_event(event))
> - perf_cgroup_mark_enabled(event, ctx);
> + /* may need to reset tstamp_enabled */
> + if (is_cgroup_event(event))
> + perf_cgroup_mark_enabled(event, ctx);

or this

>
> - if (group_can_go_on(event, cpuctx, 1))
> - group_sched_in(event, cpuctx, ctx);
> + if (group_can_go_on(event, cpuctx, 1))
> + group_sched_in(event, cpuctx, ctx);

etc, etc.

> @@ -3156,7 +3290,8 @@ ctx_sched_in(struct perf_event_context *ctx,
> struct task_struct *task)
> {
> int is_active = ctx->is_active;
> - u64 now;

Why?

> + struct perf_event *event;
> + struct rb_node *node;
>
> lockdep_assert_held(&ctx->lock);
>
> @@ -3175,7 +3310,7 @@ ctx_sched_in(struct perf_event_context *ctx,
>
> if (is_active & EVENT_TIME) {
> /* start ctx time */
> - now = perf_clock();
> + u64 now = perf_clock();

Why?

> ctx->timestamp = now;
> perf_cgroup_set_timestamp(task, ctx);
> }
> @@ -3185,11 +3320,19 @@ ctx_sched_in(struct perf_event_context *ctx,
> * in order to give them the best chance of going on.
> */
> if (is_active & EVENT_PINNED)
> - ctx_pinned_sched_in(ctx, cpuctx);
> + perf_event_groups_for_each(event, node,
> + &ctx->pinned_groups, group_node,
> + group_list, group_entry)
> + ctx_pinned_sched_in(event, cpuctx, ctx);

So this perf_event_groups_for_each() can just move into
ctx_*_sched_in(), can't it?

Regards,
--
Alex

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