Re: [PATCH v2]: perf/core: addressing 4x slowdown during per-process, profiling of STREAM benchmark on Intel Xeon Phi

Peter Zijlstra
2017-05-29T07:46:44Z

On Sat, May 27, 2017 at 02:19:51PM +0300, Alexey Budankov wrote:
> @@ -571,6 +587,27 @@ struct perf_event {
> * either sufficies for read.
> */
> struct list_head group_entry;
> + /*
> + * Node on the pinned or flexible tree located at the event context;
> + * the node may be empty in case its event is not directly attached
> + * to the tree but to group_list list of the event directly
> + * attached to the tree;
> + */
> + struct rb_node group_node;
> + /*
> + * List keeps groups allocated for the same cpu;
> + * the list may be empty in case its event is not directly
> + * attached to the tree but to group_list list of the event directly
> + * attached to the tree;
> + */
> + struct list_head group_list;
> + /*
> + * Entry into the group_list list above;
> + * the entry may be attached to the self group_list list above
> + * in case the event is directly attached to the pinned or
> + * flexible tree;
> + */
> + struct list_head group_list_entry;
> struct list_head sibling_list;
>
> /*

> @@ -742,7 +772,17 @@ struct perf_event_context {
>
> struct list_head active_ctx_list;
> struct list_head pinned_groups;
> + /*
> + * Cpu tree for pinned groups; keeps event's group_node nodes
> + * of attached flexible groups;
> + */
> + struct rb_root pinned_tree;
> struct list_head flexible_groups;
> + /*
> + * Cpu tree for flexible groups; keeps event's group_node nodes
> + * of attached flexible groups;
> + */
> + struct rb_root flexible_tree;
> struct list_head event_list;
> int nr_events;
> int nr_active;
> @@ -758,6 +798,7 @@ struct perf_event_context {
> */
> u64 time;
> u64 timestamp;
> + struct perf_event_tstamp tstamp_data;
>
> /*
> * These fields let us detect when two contexts have both

So why do we now have a list _and_ a tree for the same entries?