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.
Tested-by: Arun Sharma <[email protected]> Tested-by: Rodrigo Campos <[email protected]> Acked-by: Jiri Olsa <[email protected]> Cc: Frederic Weisbecker <[email protected]> Signed-off-by: Namhyung Kim <[email protected]> --- tools/perf/util/hist.c | 44 ++++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 44 insertions(+) diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c index 802af8495f83..b3faabf3d2c2 100644 --- a/tools/perf/util/hist.c +++ b/tools/perf/util/hist.c @@ -704,7 +704,22 @@ static int iter_prepare_cumulative_entry(struct hist_entry_iter *iter __maybe_unused, struct addr_location *al __maybe_unused) { + 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; + return 0; } @@ -714,6 +729,7 @@ iter_add_single_cumulative_entry(struct hist_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; he = __hists__add_entry(&evsel->hists, al, iter->parent, NULL, NULL, @@ -723,6 +739,8 @@ iter_add_single_cumulative_entry(struct hist_entry_iter *iter, return -ENOMEM; iter->he = he; + he_cache[iter->curr++] = he; + return hist_entry__inc_addr_samples(he, evsel->idx, al->addr); } @@ -747,7 +765,29 @@ iter_add_next_cumulative_entry(struct hist_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 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, @@ -755,6 +795,8 @@ iter_add_next_cumulative_entry(struct hist_entry_iter *iter, if (he == NULL) return -ENOMEM; + he_cache[iter->curr++] = he; + return hist_entry__inc_addr_samples(he, evsel->idx, al->addr); } @@ -765,6 +807,8 @@ iter_finish_cumulative_entry(struct hist_entry_iter *iter, struct perf_evsel *evsel = iter->evsel; struct hist_entry *he = iter->he; + zfree(&iter->priv); + if (he == NULL) return 0; -- 1.9.2 -- To unsubscribe from this list: send the line "unsubscribe linux-kernel" in the body of a message to [email protected] More majordomo info at http://vger.kernel.org/majordomo-info.html Please read the FAQ at http://www.tux.org/lkml/
