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perf report: Cache cumulative callchains

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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 <namhyung@kernel.org>
Tested-by: Arun Sharma <asharma@fb.com>
Tested-by: Rodrigo Campos <rodrigo@sdfg.com.ar>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Link: http://lkml.kernel.org/r/1401335910-16832-8-git-send-email-namhyung@kernel.org
Signed-off-by: Jiri Olsa <jolsa@kernel.org>
This commit is contained in:
Namhyung Kim 2013-10-31 10:05:29 +09:00 committed by Jiri Olsa
parent c7405d85d7
commit b4d3c8bd86
1 changed files with 42 additions and 0 deletions
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42
tools/perf/util/hist.c
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@ -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;
}