linux-kernel - Re: [PATCH 14/37] perf tools: Convert dead thread list into rbtree

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Date:	Fri, 26 Dec 2014 00:05:52 +0100
From:	Jiri Olsa <jolsa@...hat.com>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Arnaldo Carvalho de Melo <acme@...nel.org>,
	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Stephane Eranian <eranian@...gle.com>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH 14/37] perf tools: Convert dead thread list into rbtree

On Wed, Dec 24, 2014 at 04:15:10PM +0900, Namhyung Kim wrote:

SNIP

>  
>  static void machine__remove_thread(struct machine *machine, struct thread *th)
>  {
> +	struct rb_node **p = &machine->dead_threads.rb_node;
> +	struct rb_node *parent = NULL;
> +	struct thread *pos;
> +
>  	machine->last_match = NULL;
>  	rb_erase(&th->rb_node, &machine->threads);
> +
> +	th->dead = true;
> +
>  	/*
>  	 * We may have references to this thread, for instance in some hist_entry
> -	 * instances, so just move them to a separate list.
> +	 * instances, so just move them to a separate list in rbtree.
>  	 */
> -	list_add_tail(&th->node, &machine->dead_threads);
> +	while (*p != NULL) {
> +		parent = *p;
> +		pos = rb_entry(parent, struct thread, rb_node);
> +
> +		if (pos->tid == th->tid) {
> +			list_add_tail(&th->node, &pos->node);
> +			return;
> +		}

hum, why is this 'new list' in thread object necessary? why not
to store all in the tree?


> +
> +		if (th->tid < pos->tid)
> +			p = &(*p)->rb_left;
> +		else
> +			p = &(*p)->rb_right;
> +	}
> +

SNIP

> diff --git a/tools/perf/util/thread.h b/tools/perf/util/thread.h
> index 0b6dcd70bc8b..413f28cf689b 100644
> --- a/tools/perf/util/thread.h
> +++ b/tools/perf/util/thread.h
> @@ -11,10 +11,8 @@
>  struct thread_stack;
>  
>  struct thread {
> -	union {
> -		struct rb_node	 rb_node;
> -		struct list_head node;
> -	};
> +	struct rb_node	 	rb_node;
> +	struct list_head 	node;
>  	struct map_groups	*mg;
>  	pid_t			pid_; /* Not all tools update this */
>  	pid_t			tid;
> @@ -22,7 +20,8 @@ struct thread {
>  	int			cpu;
>  	char			shortname[3];
>  	bool			comm_set;
> -	bool			dead; /* if set thread has exited */
> +	bool			exited; /* if set thread has exited */
> +	bool			dead; /* thread is in dead_threads list */

looks like this also changes the logic (new exited flag),
not just the dead threads storage wheel

jirka
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