perf stat: Only auto-merge events that are PMU aliases

Peter reported that when he explicitely asked for multiple events with
the same name on the command line it got coalesced into just one line,
i.e.:

   # perf stat -e cycles -e cycles -e cycles usleep 1

   Performance counter stats for 'usleep 1':

         3,269,652      cycles

       0.000884123 seconds time elapsed

  #

And while there is the --no-merges option to disable that auto-merging,
this is a blunt change in behaviour for such explicit request, so change
the code so that this auto merging is done only when handling the multi
PMU aliases with the same name that introduced this coalescing,
restoring the previous behaviour for the explicit case:

  # perf stat -e cycles -e cycles -e cycles usleep 1

   Performance counter stats for 'usleep 1':

         1,472,837      cycles
         1,472,837      cycles
         1,472,837      cycles

       0.001764870 seconds time elapsed

  #

Reported-by: Peter Zijlstra <peterz@infradead.org>
Acked-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Cc: Adrian Hunter <adrian.hunter@intel.com>
Cc: Mark Rutland <mark.rutland@arm.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Wang Nan <wangnan0@huawei.com>
Fixes: 430daf2dc7af ("perf stat: Collapse identically named events")
Link: http://lkml.kernel.org/r/20170831184122.GK4831@kernel.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 1 insertions, 0 deletions

diff --git a/tools/perf/util/evsel.h b/tools/perf/util/evsel.h
index 351d3b2d8887..dd2c4b5112a5 100644
--- a/tools/perf/util/evsel.h
+++ b/tools/perf/util/evsel.h
@@ -131,6 +131,7 @@ struct perf_evsel {
 	bool			cmdline_group_boundary;
 	struct list_head	config_terms;
 	int			bpf_fd;
+	bool			auto_merge_stats;
 	bool			merged_stat;
 	const char *		metric_expr;
 	const char *		metric_name;