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

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Date:	Tue,  5 Jan 2016 12:06:00 +0900
From:	Namhyung Kim <namhyung@...nel.org>
To:	Arnaldo Carvalho de Melo <acme@...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: [PATCH] perf top: Decay periods in callchains

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.

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

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