A metric like DRAM_BW_Use has on SkylakeX events uncore_imc/cas_count_read/
and uncore_imc/case_count_write/. These events open 6 events per socket
with pmu names of uncore_imc_[0-5]. The current metric setup code in
find_evsel_group assumes one ID will map to 1 event to be recorded in
metric_events. For events with multiple matches, the first event is
recorded in metric_events (avoiding matching >1 event with the same
name) and the evlist_used updated so that duplicate events aren't
removed when the evlist has unused events removed.
Before this change:
$ /tmp/perf/perf stat -M DRAM_BW_Use -a -- sleep 1
Performance counter stats for 'system wide':
41.14 MiB uncore_imc/cas_count_read/
1,002,614,251 ns duration_time
1.002614251 seconds time elapsed
After this change:
$ /tmp/perf/perf stat -M DRAM_BW_Use -a -- sleep 1
Performance counter stats for 'system wide':
157.47 MiB uncore_imc/cas_count_read/ # 0.00 DRAM_BW_Use
126.97 MiB uncore_imc/cas_count_write/
1,003,019,728 ns duration_time
v3. cleans up searching for the same event within metric_events to use a
helper and avoids a redundant search. It uses a continue loop to
make the search for similarly named events shorter.
v2. avoids iterating over the whole evlist as suggested by
namhy...@kernel.org. It also fixes the metric_leader computation
that was broken in the same commits.
Erroneous duplication introduced in:
commit 2440689d62e9 ("perf metricgroup: Remove duped metric group events").
Fixes: ded80bda8bc9 ("perf expr: Migrate expr ids table to a hashmap").
Reported-by: Jin Yao <yao....@linux.intel.com>
Signed-off-by: Ian Rogers <irog...@google.com>
---
tools/perf/util/metricgroup.c | 75 ++++++++++++++++++++++++++---------
1 file changed, 56 insertions(+), 19 deletions(-)
diff --git a/tools/perf/util/metricgroup.c b/tools/perf/util/metricgroup.c
index 662f4e8777d5..7b66452cb9f9 100644
--- a/tools/perf/util/metricgroup.c
+++ b/tools/perf/util/metricgroup.c
@@ -149,6 +149,18 @@ static void expr_ids__exit(struct expr_ids *ids)
free(ids->id[i].id);
}
+static bool contains_event(struct evsel **metric_events, int num_events,
+ const char *event_name)
+{
+ int i;
+
+ for (i = 0; i < num_events; i++) {
+ if (!strcmp(metric_events[i]->name, event_name))
+ return true;
+ }
+ return false;
+}
+
/**
* Find a group of events in perf_evlist that correspond to those from a parsed
* metric expression. Note, as find_evsel_group is called in the same order as
@@ -179,7 +191,11 @@ static struct evsel *find_evsel_group(struct evlist
*perf_evlist,
int i = 0, matched_events = 0, events_to_match;
const int idnum = (int)hashmap__size(&pctx->ids);
- /* duration_time is grouped separately. */
+ /*
+ * duration_time is always grouped separately, when events are grouped
+ * (ie has_constraint is false) then ignore it in the matching loop and
+ * add it to metric_events at the end.
+ */
if (!has_constraint &&
hashmap__find(&pctx->ids, "duration_time", (void **)&val_ptr))
events_to_match = idnum - 1;
@@ -206,23 +222,20 @@ static struct evsel *find_evsel_group(struct evlist
*perf_evlist,
sizeof(struct evsel *) * idnum);
current_leader = ev->leader;
}
- if (hashmap__find(&pctx->ids, ev->name, (void **)&val_ptr)) {
- if (has_constraint) {
- /*
- * Events aren't grouped, ensure the same event
- * isn't matched from two groups.
- */
- for (i = 0; i < matched_events; i++) {
- if (!strcmp(ev->name,
- metric_events[i]->name)) {
- break;
- }
- }
- if (i != matched_events)
- continue;
- }
+ /*
+ * Check for duplicate events with the same name. For example,
+ * uncore_imc/cas_count_read/ will turn into 6 events per socket
+ * on skylakex. Only the first such event is placed in
+ * metric_events. If events aren't grouped then this also
+ * ensures that the same event in different sibling groups
+ * aren't both added to metric_events.
+ */
+ if (contains_event(metric_events, matched_events, ev->name))
+ continue;
+ /* Does this event belong to the parse context? */
+ if (hashmap__find(&pctx->ids, ev->name, (void **)&val_ptr))
metric_events[matched_events++] = ev;
- }
+
if (matched_events == events_to_match)
break;
}
@@ -238,7 +251,7 @@ static struct evsel *find_evsel_group(struct evlist
*perf_evlist,
}
if (matched_events != idnum) {
- /* Not whole match */
+ /* Not a whole match */
return NULL;
}
@@ -246,8 +259,32 @@ static struct evsel *find_evsel_group(struct evlist
*perf_evlist,
for (i = 0; i < idnum; i++) {
ev = metric_events[i];
- ev->metric_leader = ev;
+ /* Don't free the used events. */
set_bit(ev->idx, evlist_used);
+ /*
+ * The metric leader points to the identically named event in
+ * metric_events.
+ */
+ ev->metric_leader = ev;
+ /*
+ * Mark two events with identical names in the same group (or
+ * globally) as being in use as uncore events may be duplicated
+ * for each pmu. Set the metric leader of such events to be the
+ * event that appears in metric_events.
+ */
+ evlist__for_each_entry_continue(perf_evlist, ev) {
+ /*
+ * If events are grouped then the search can terminate
+ * when then group is left.
+ */
+ if (!has_constraint &&
+ ev->leader != metric_events[i]->leader)
+ break;
+ if (!strcmp(metric_events[i]->name, ev->name)) {
+ set_bit(ev->idx, evlist_used);
+ ev->metric_leader = metric_events[i];
+ }
+ }
}
return metric_events[0];
--
2.28.0.526.ge36021eeef-goog
