From b4d3c8bd86c4eda08456691121f83b4e1db46866 Mon Sep 17 00:00:00 2001 From: Namhyung Kim Date: Thu, 31 Oct 2013 10:05:29 +0900 Subject: [PATCH] perf report: Cache cumulative callchains 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. Signed-off-by: Namhyung Kim Tested-by: Arun Sharma Tested-by: Rodrigo Campos Cc: Frederic Weisbecker Link: http://lkml.kernel.org/r/1401335910-16832-8-git-send-email-namhyung@kernel.org Signed-off-by: Jiri Olsa --- tools/perf/util/hist.c | 42 ++++++++++++++++++++++++++++++++++++++++++ 1 file changed, 42 insertions(+) diff --git a/tools/perf/util/hist.c b/tools/perf/util/hist.c index 37c28fc13dc3..bf03db528db6 100644 --- a/tools/perf/util/hist.c +++ b/tools/perf/util/hist.c @@ -700,7 +700,22 @@ 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; } @@ -710,6 +725,7 @@ 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; int err = 0; @@ -720,6 +736,7 @@ iter_add_single_cumulative_entry(struct hist_entry_iter *iter, return -ENOMEM; iter->he = he; + he_cache[iter->curr++] = he; /* * The iter->he will be over-written after ->add_next_entry() @@ -754,7 +771,29 @@ 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, @@ -763,6 +802,7 @@ iter_add_next_cumulative_entry(struct hist_entry_iter *iter, return -ENOMEM; iter->he = he; + he_cache[iter->curr++] = he; return 0; } @@ -771,7 +811,9 @@ static int iter_finish_cumulative_entry(struct hist_entry_iter *iter, struct addr_location *al __maybe_unused) { + zfree(&iter->priv); iter->he = NULL; + return 0; } -- 2.11.0