libperf: Propagate maps only if necessary

The current code propagate evsel's cpu map settings to evlist when it's
added to an evlist. But the evlist->all_cpus and each evsel's cpus will
be updated in perf_evlist__set_maps() later. No need to do it before
evlist's cpus are set actually.

In fact it discards this intermediate all_cpus maps at the beginning
of perf_evlist__set_maps(). Let's not do this. It's only needed when
an evsel is added after the evlist cpu/thread maps are set.

Reviewed-by: Adrian Hunter <[e-mail]>
Signed-off-by: Namhyung Kim <[e-mail]>
Cc: Ian Rogers <[e-mail]>
Cc: Ingo Molnar <[e-mail]>
Cc: Jiri Olsa <[e-mail]>
Cc: Kan Liang <[e-mail]>
Cc: Leo Yan <[e-mail]>
Cc: Peter Zijlstra <[e-mail]>
Link: https://lore.kernel.org/r/[e-mail]
Signed-off-by: Arnaldo Carvalho de Melo <[e-mail]>

tools/lib/perf/evlist.c

···
 {
 	struct perf_evsel *evsel;
 
-	/* Recomputing all_cpus, so start with a blank slate. */
-	perf_cpu_map__put(evlist->all_cpus);
-	evlist->all_cpus = NULL;
+	evlist->needs_map_propagation = true;
 
 	perf_evlist__for_each_evsel(evlist, evsel)
 		__perf_evlist__propagate_maps(evlist, evsel);
···
 	evsel->idx = evlist->nr_entries;
 	list_add_tail(&evsel->node, &evlist->entries);
 	evlist->nr_entries += 1;
-	__perf_evlist__propagate_maps(evlist, evsel);
+
+	if (evlist->needs_map_propagation)
+		__perf_evlist__propagate_maps(evlist, evsel);
 }
 
 void perf_evlist__remove(struct perf_evlist *evlist,
···
 		perf_thread_map__put(evlist->threads);
 		evlist->threads = perf_thread_map__get(threads);
 	}
-
-	if (!evlist->all_cpus && cpus)
-		evlist->all_cpus = perf_cpu_map__get(cpus);
 
 	perf_evlist__propagate_maps(evlist);
 }

tools/lib/perf/include/internal/evlist.h

···
 	int			 nr_entries;
 	int			 nr_groups;
 	bool			 has_user_cpus;
+	bool			 needs_map_propagation;
 	/**
 	 * The cpus passed from the command line or all online CPUs by
 	 * default.