From: Namhyung Kim <namhyung....@lge.com>
It is possble that a callchain has cycles or recursive calls. In that
case it'll end up having entries more than 100% overhead in the
output. In order to prevent such entries, cache each callchain node
and skip if same entry already cumulated.
Cc: Arun Sharma <asha...@fb.com>
Cc: Frederic Weisbecker <fweis...@gmail.com>
Signed-off-by: Namhyung Kim <namhy...@kernel.org>
---
tools/perf/builtin-report.c | 48 +++++++++++++++++++++++++++++++++++++++++++++
1 file changed, 48 insertions(+)
diff --git a/tools/perf/builtin-report.c b/tools/perf/builtin-report.c
index 80c774615287..4ec1a090d1a3 100644
--- a/tools/perf/builtin-report.c
+++ b/tools/perf/builtin-report.c
@@ -406,8 +406,27 @@ iter_prepare_cumulative_entry(struct add_entry_iter *iter,
struct addr_location *al __maybe_unused,
struct perf_sample *sample)
{
+ struct callchain_cursor_node *node;
+ struct hist_entry **he_cache;
+
callchain_cursor_commit(&callchain_cursor);
+ /*
+ * This is for detecting cycles or recursions so that they're
+ * cumulated only one time to prevent entries more than 100%
+ * overhead.
+ */
+ he_cache = malloc(sizeof(*he_cache) * (PERF_MAX_STACK_DEPTH + 1));
+ if (he_cache == NULL)
+ return -ENOMEM;
+
+ iter->priv = he_cache;
+ iter->curr = 0;
+
+ node = callchain_cursor_current(&callchain_cursor);
+ if (node == NULL)
+ return 0;
+
iter->evsel = evsel;
iter->sample = sample;
iter->machine = machine;
@@ -420,6 +439,7 @@ iter_add_single_cumulative_entry(struct add_entry_iter
*iter,
{
struct perf_evsel *evsel = iter->evsel;
struct perf_sample *sample = iter->sample;
+ struct hist_entry **he_cache = iter->priv;
struct hist_entry *he;
int err = 0;
@@ -429,6 +449,8 @@ iter_add_single_cumulative_entry(struct add_entry_iter
*iter,
if (he == NULL)
return -ENOMEM;
+ he_cache[iter->curr++] = he;
+
/*
* This is for putting parents upward during output resort iff
* only a child gets sampled. See hist_entry__sort_on_period().
@@ -510,8 +532,30 @@ iter_add_next_cumulative_entry(struct add_entry_iter *iter,
{
struct perf_evsel *evsel = iter->evsel;
struct perf_sample *sample = iter->sample;
+ struct hist_entry **he_cache = iter->priv;
struct hist_entry *he;
+ struct hist_entry he_tmp = {
+ .cpu = al->cpu,
+ .thread = al->thread,
+ .comm = thread__comm(al->thread),
+ .ip = al->addr,
+ .ms = {
+ .map = al->map,
+ .sym = al->sym,
+ },
+ .parent = iter->parent,
+ };
int err = 0;
+ int i;
+
+ /*
+ * Check if there's duplicate entries in the callchain.
+ * It's possible that it has cycles or recursive calls.
+ */
+ for (i = 0; i < iter->curr; i++) {
+ if (hist_entry__cmp(he_cache[i], &he_tmp) == 0)
+ return 0;
+ }
he = __hists__add_entry(&evsel->hists, al, iter->parent, NULL, NULL,
sample->period, sample->weight,
@@ -519,6 +563,8 @@ iter_add_next_cumulative_entry(struct add_entry_iter *iter,
if (he == NULL)
return -ENOMEM;
+ he_cache[iter->curr++] = he;
+
/*
* Only in the TUI browser we are doing integrated annotation,
* so we don't allocated the extra space needed because the stdio
@@ -547,6 +593,8 @@ iter_finish_cumulative_entry(struct add_entry_iter *iter,
evsel->hists.stats.total_period += sample->period;
hists__inc_nr_events(&evsel->hists, PERF_RECORD_SAMPLE);
+ free(iter->priv);
+ iter->priv = NULL;
return 0;
}
--
1.7.11.7
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