[PATCH v3 1/2] perf evlist: Allow setting arbitrary leader

From: Ian Rogers
Date: Tue Nov 30 2021 - 12:50:52 EST


The leader of a group is the first, but allow it to be an arbitrary
list member so that for Intel topdown events slots may always be the
group leader.

v3. Switched list_entry to list_first_entry as suggested by Arnaldo
Carvalho de Melo <acme@xxxxxxxxxx>.

Reviewed-by: Kajol Jain<kjain@xxxxxxxxxxxxx>
Acked-by: Jiri Olsa <jolsa@xxxxxxxxxx>
Signed-off-by: Ian Rogers <irogers@xxxxxxxxxx>
---
tools/lib/perf/evlist.c | 15 +++++++++------
tools/lib/perf/include/internal/evlist.h | 2 +-
tools/perf/util/parse-events.c | 4 ++--
3 files changed, 12 insertions(+), 9 deletions(-)

diff --git a/tools/lib/perf/evlist.c b/tools/lib/perf/evlist.c
index e37dfad31383..245acbc53bd3 100644
--- a/tools/lib/perf/evlist.c
+++ b/tools/lib/perf/evlist.c
@@ -643,14 +643,14 @@ perf_evlist__next_mmap(struct perf_evlist *evlist, struct perf_mmap *map,
return overwrite ? evlist->mmap_ovw_first : evlist->mmap_first;
}

-void __perf_evlist__set_leader(struct list_head *list)
+void __perf_evlist__set_leader(struct list_head *list, struct perf_evsel *leader)
{
- struct perf_evsel *evsel, *leader;
+ struct perf_evsel *first, *last, *evsel;

- leader = list_entry(list->next, struct perf_evsel, node);
- evsel = list_entry(list->prev, struct perf_evsel, node);
+ first = list_first_entry(list, struct perf_evsel, node);
+ last = list_last_entry(list, struct perf_evsel, node);

- leader->nr_members = evsel->idx - leader->idx + 1;
+ leader->nr_members = last->idx - first->idx + 1;

__perf_evlist__for_each_entry(list, evsel)
evsel->leader = leader;
@@ -659,7 +659,10 @@ void __perf_evlist__set_leader(struct list_head *list)
void perf_evlist__set_leader(struct perf_evlist *evlist)
{
if (evlist->nr_entries) {
+ struct perf_evsel *first = list_entry(evlist->entries.next,
+ struct perf_evsel, node);
+
evlist->nr_groups = evlist->nr_entries > 1 ? 1 : 0;
- __perf_evlist__set_leader(&evlist->entries);
+ __perf_evlist__set_leader(&evlist->entries, first);
}
}
diff --git a/tools/lib/perf/include/internal/evlist.h b/tools/lib/perf/include/internal/evlist.h
index f366dbad6a88..6f74269a3ad4 100644
--- a/tools/lib/perf/include/internal/evlist.h
+++ b/tools/lib/perf/include/internal/evlist.h
@@ -127,5 +127,5 @@ int perf_evlist__id_add_fd(struct perf_evlist *evlist,

void perf_evlist__reset_id_hash(struct perf_evlist *evlist);

-void __perf_evlist__set_leader(struct list_head *list);
+void __perf_evlist__set_leader(struct list_head *list, struct perf_evsel *leader);
#endif /* __LIBPERF_INTERNAL_EVLIST_H */
diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 5bfb6f892489..c2935aca4b67 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -1834,8 +1834,8 @@ void parse_events__set_leader(char *name, struct list_head *list,
if (parse_events__set_leader_for_uncore_aliase(name, list, parse_state))
return;

- __perf_evlist__set_leader(list);
- leader = list_entry(list->next, struct evsel, core.node);
+ leader = list_first_entry(list, struct evsel, core.node);
+ __perf_evlist__set_leader(list, &leader->core);
leader->group_name = name ? strdup(name) : NULL;
}

--
2.34.0.rc2.393.gf8c9666880-goog