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Date: Mon, 29 May 2017 09:46:36 +0200
From: Peter Zijlstra <peterz@infradead.org>
To: Alexey Budankov <alexey.budankov@linux.intel.com>
Cc: Ingo Molnar <mingo@redhat.com>,
        Arnaldo Carvalho de Melo <acme@kernel.org>,
        Alexander Shishkin <alexander.shishkin@linux.intel.com>,
        Andi Kleen <ak@linux.intel.com>, Kan Liang <kan.liang@intel.com>,
        Dmitri Prokhorov <Dmitry.Prohorov@intel.com>,
        Valery Cherepennikov <valery.cherepennikov@intel.com>,
        David Carrillo-Cisneros <davidcc@google.com>,
        Stephane Eranian <eranian@google.com>,
        Mark Rutland <mark.rutland@arm.com>, linux-kernel@vger.kernel.org
Subject: Re: [PATCH v2]: perf/core: addressing 4x slowdown during
 per-process, profiling of STREAM benchmark on Intel Xeon Phi
Message-ID: <20170529074636.tjftcdtcg6op74i3@hirez.programming.kicks-ass.net>
References: <1e962b59-3e39-e0d6-515d-c4fd3502edae@linux.intel.com>
 <b410f376-69ed-c681-8413-c4186bc74aed@linux.intel.com>
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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?