linux-kernel - Re: [PATCH 14/40] perf tools: Introduce machine__find*_thread_by

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Message-ID: <20150518195006.GD12169@krava>
Date:	Mon, 18 May 2015 21:50:06 +0200
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>,
	Adrian Hunter <adrian.hunter@...el.com>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>,
	Stephane Eranian <eranian@...gle.com>
Subject: Re: [PATCH 14/40] perf tools: Introduce
 machine__find*_thread_by_time()

On Mon, May 18, 2015 at 09:30:29AM +0900, Namhyung Kim wrote:

SNIP

> +static struct thread *
> +__machine__findnew_thread_by_time(struct machine *machine, pid_t pid, pid_t tid,
> +				  u64 timestamp, bool create)
> +{
> +	struct thread *curr, *pos, *new;
> +	struct thread *th = NULL;
> +	struct rb_node **p;
> +	struct rb_node *parent = NULL;
> +
> +	if (!perf_has_index)
> +		return ____machine__findnew_thread(machine, pid, tid, create);
> +
> +	/* lookup current thread first */
> +	curr = ____machine__findnew_thread(machine, pid, tid, false);
> +	if (curr && timestamp >= curr->start_time)
> +		return curr;
> +
> +	/* and then check dead threads tree & list */
> +	p = &machine->dead_threads.rb_node;
> +	while (*p != NULL) {
> +		parent = *p;
> +		th = rb_entry(parent, struct thread, rb_node);
> +
> +		if (th->tid == tid) {
> +			list_for_each_entry(pos, &th->tid_node, tid_node) {
> +				if (timestamp >= pos->start_time &&
> +				    pos->start_time > th->start_time) {
> +					th = pos;
> +					break;
> +				}

hum, how do we know, there's not another thread on the list
fitting the timestamp >= pos->start_time condition as well?

jirka
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