[PATCH 42/59] perf top: Decay periods in callchains

From: Arnaldo Carvalho de Melo
Date: Fri Jan 08 2016 - 13:04:45 EST


From: Namhyung Kim <namhyung@xxxxxxxxxx>

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@xxxxxxxxxx>
Signed-off-by: Namhyung Kim <namhyung@xxxxxxxxxx>
Cc: Andi Kleen <andi@xxxxxxxxxxxxxx>
Cc: David Ahern <dsahern@xxxxxxxxx>
Cc: Frederic Weisbecker <fweisbec@xxxxxxxxx>
Cc: Jiri Olsa <jolsa@xxxxxxxxxx>
Cc: Peter Zijlstra <a.p.zijlstra@xxxxxxxxx>
Link: http://lkml.kernel.org/r/1451963160-17196-1-git-send-email-namhyung@xxxxxxxxxx
Signed-off-by: Arnaldo Carvalho de Melo <acme@xxxxxxxxxx>
---
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;

--
2.1.0