Re: [PATCH v5 1/4]: perf/core: use rb trees for pinned/flexible groups

From: Alexander Shishkin
Date: Tue Jul 18 2017 - 08:03:07 EST


Alexey Budankov <alexey.budankov@xxxxxxxxxxxxxxx> writes:

> +static void
> +perf_event_groups_rotate(struct perf_event_groups *groups, int cpu)
> +{
> + struct rb_node *node;
> + struct perf_event *node_event;
> +
> + WARN_ON_ONCE(!groups);

This seems redundant.

> +
> + list_rotate_left(&groups->list);
> +
> + /* will replace rotation above in patch v5 3/4
> +
> + node = groups->tree.rb_node;
> +
> + while (node) {
> + node_event = container_of(node,
> + struct perf_event, group_node);
> +
> + if (cpu < node_event->cpu) {
> + node = node->rb_left;
> + } else if (cpu > node_event->cpu) {
> + node = node->rb_right;
> + } else {
> + list_rotate_left(&node_event->group_list);
> + break;
> + }
> + }
> +
> + */

Please don't do this, it doesn't add clarity.

> +static int
> +perf_event_groups_iterate(struct perf_event_groups *groups,
> + perf_event_groups_iterate_f callback, void *data)
> +{
> + int ret = 0;
> + struct perf_event *event;
> +
> + WARN_ON_ONCE(!groups);
> +
> + list_for_each_entry(event, &groups->list, group_list_entry) {
> + ret = callback(event, data);
> + if (ret)
> + break;
> + }
> +
> + /* will replace itration above in patch v5 4/4
> +
> + for (node = rb_first(groups); node; node = rb_next(node)) {
> + node_event = container_of(node, struct perf_event, group_node);
> + list_for_each_entry(event, &node_event->group_list,
> + group_list_entry) {
> + WARN_ON_ONCE(!(event->cpu == node_event->cpu));
> + ret = callback(event, data);
> + if (ret) {
> + return ret;
> + }
> + }
> + }
> +
> + */

Ditto.

Regards,
--
Alex