linux-kernel - [tip:perf/core] perf top: Decay periods in callchains

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Date:	Sat, 9 Jan 2016 08:36:34 -0800
From:	tip-bot for Namhyung Kim <tipbot@...or.com>
To:	linux-tip-commits@...r.kernel.org
Cc:	acme@...nel.org, linux-kernel@...r.kernel.org, mingo@...nel.org,
	hpa@...or.com, acme@...hat.com, andi@...stfloor.org,
	fweisbec@...il.com, a.p.zijlstra@...llo.nl, namhyung@...nel.org,
	jolsa@...hat.com, dsahern@...il.com, tglx@...utronix.de
Subject: [tip:perf/core] perf top: Decay periods in callchains

Commit-ID:  42b276a2351517409d55b1202a1fa8b05c0cdc99
Gitweb:     http://git.kernel.org/tip/42b276a2351517409d55b1202a1fa8b05c0cdc99
Author:     Namhyung Kim <namhyung@...nel.org>
AuthorDate: Tue, 5 Jan 2016 12:06:00 +0900
Committer:  Arnaldo Carvalho de Melo <acme@...hat.com>
CommitDate: Fri, 8 Jan 2016 12:37:51 -0300

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>
Cc: Andi Kleen <andi@...stfloor.org>
Cc: David Ahern <dsahern@...il.com>
Cc: Frederic Weisbecker <fweisbec@...il.com>
Cc: Jiri Olsa <jolsa@...hat.com>
Cc: Peter Zijlstra <a.p.zijlstra@...llo.nl>
Link: http://lkml.kernel.org/r/1451963160-17196-1-git-send-email-namhyung@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 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 564377d..53c43eb 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 8ac8f043..18dd222 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 afc9b8f..888776b 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;