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

[Peter Zijlstra]

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?