linux-kernel - Re: [PATCH] perf top: Decay periods in callchains

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Date:	Fri, 8 Jan 2016 12:38:26 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Namhyung Kim <namhyung@...nel.org>
Cc:	Ingo Molnar <mingo@...nel.org>,
	Peter Zijlstra <a.p.zijlstra@...llo.nl>,
	Jiri Olsa <jolsa@...hat.com>,
	LKML <linux-kernel@...r.kernel.org>,
	David Ahern <dsahern@...il.com>,
	Andi Kleen <andi@...stfloor.org>,
	Frederic Weisbecker <fweisbec@...il.com>
Subject: Re: [PATCH] perf top: Decay periods in callchains

Em Tue, Jan 05, 2016 at 12:06:00PM +0900, Namhyung Kim escreveu:
> It missed to decay periods in callchains when decaying hist entries.
> This resulted in more than 100 percent overhead in callchains in the
> fractal style output.

Thanks, applied!
 
> Reported-by: Arnaldo Carvalho de Melo <acme@...nel.org>
> Signed-off-by: Namhyung Kim <namhyung@...nel.org>
> ---
>  tools/perf/util/callchain.c | 28 ++++++++++++++++++++++++++++
>  tools/perf/util/callchain.h |  1 +
>  tools/perf/util/hist.c      |  1 +
>  3 files changed, 30 insertions(+)
> 
> diff --git a/tools/perf/util/callchain.c b/tools/perf/util/callchain.c
> index 564377d2bebf..53c43eb9489e 100644
> --- a/tools/perf/util/callchain.c
> +++ b/tools/perf/util/callchain.c
> @@ -925,6 +925,34 @@ void free_callchain(struct callchain_root *root)
>  	free_callchain_node(&root->node);
>  }
>  
> +static u64 decay_callchain_node(struct callchain_node *node)
> +{
> +	struct callchain_node *child;
> +	struct rb_node *n;
> +	u64 child_hits = 0;
> +
> +	n = rb_first(&node->rb_root_in);
> +	while (n) {
> +		child = container_of(n, struct callchain_node, rb_node_in);
> +
> +		child_hits += decay_callchain_node(child);
> +		n = rb_next(n);
> +	}
> +
> +	node->hit = (node->hit * 7) / 8;
> +	node->children_hit = child_hits;
> +
> +	return node->hit;
> +}
> +
> +void decay_callchain(struct callchain_root *root)
> +{
> +	if (!symbol_conf.use_callchain)
> +		return;
> +
> +	decay_callchain_node(&root->node);
> +}
> +
>  int callchain_node__make_parent_list(struct callchain_node *node)
>  {
>  	struct callchain_node *parent = node->parent;
> diff --git a/tools/perf/util/callchain.h b/tools/perf/util/callchain.h
> index 8ac8f043004c..18dd22269764 100644
> --- a/tools/perf/util/callchain.h
> +++ b/tools/perf/util/callchain.h
> @@ -253,6 +253,7 @@ int callchain_node__fprintf_value(struct callchain_node *node,
>  				  FILE *fp, u64 total);
>  
>  void free_callchain(struct callchain_root *root);
> +void decay_callchain(struct callchain_root *root);
>  int callchain_node__make_parent_list(struct callchain_node *node);
>  
>  #endif	/* __PERF_CALLCHAIN_H */
> diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c
> index afc9b8f1b36c..888776b43cb0 100644
> --- a/tools/perf/util/hist.c
> +++ b/tools/perf/util/hist.c
> @@ -254,6 +254,7 @@ static bool hists__decay_entry(struct hists *hists, struct hist_entry *he)
>  	he_stat__decay(&he->stat);
>  	if (symbol_conf.cumulate_callchain)
>  		he_stat__decay(he->stat_acc);
> +	decay_callchain(he->callchain);
>  
>  	diff = prev_period - he->stat.period;
>  
> -- 
> 2.6.4