linux-kernel - [PATCH 2/4] perf stat: Always keep perf metrics topdown events in a group

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Date:   Fri, 13 May 2022 08:15:52 -0700
From:   kan.liang@...ux.intel.com
To:     acme@...nel.org, mingo@...hat.com, irogers@...gle.com,
        jolsa@...nel.org, namhyung@...nel.org,
        linux-kernel@...r.kernel.org, linux-perf-users@...r.kernel.org
Cc:     peterz@...radead.org, zhengjun.xing@...ux.intel.com,
        adrian.hunter@...el.com, ak@...ux.intel.com, eranian@...gle.com,
        Kan Liang <kan.liang@...ux.intel.com>
Subject: [PATCH 2/4] perf stat: Always keep perf metrics topdown events in a group

From: Kan Liang <kan.liang@...ux.intel.com>

If any member in a group has a different cpu mask than the other
members, the current perf stat disables group. when the perf metrics
topdown events are part of the group, the below <not supported> error
will be triggered.

$ perf stat -e "{slots,topdown-retiring,uncore_imc_free_running_0/dclk/}" -a sleep 1
WARNING: grouped events cpus do not match, disabling group:
  anon group { slots, topdown-retiring, uncore_imc_free_running_0/dclk/ }

 Performance counter stats for 'system wide':

       141,465,174      slots
   <not supported>      topdown-retiring
     1,605,330,334      uncore_imc_free_running_0/dclk/

The perf metrics topdown events must always be grouped with a slots
event as leader.

With the patch, the topdown events aren't broken from the group for the
splitting.

$ perf stat -e "{slots,topdown-retiring,uncore_imc_free_running_0/dclk/}" -a sleep 1
WARNING: grouped events cpus do not match, disabling group:
  anon group { slots, topdown-retiring, uncore_imc_free_running_0/dclk/ }

 Performance counter stats for 'system wide':

       346,110,588      slots
       124,608,256      topdown-retiring
     1,606,869,976      uncore_imc_free_running_0/dclk/

       1.003877592 seconds time elapsed

Fixes: a9a1790247bd ("perf stat: Ensure group is defined on top of the same cpu mask")
Signed-off-by: Kan Liang <kan.liang@...ux.intel.com>
---
 tools/perf/builtin-stat.c | 7 +++++--
 1 file changed, 5 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index a96f106dc93a..af2248868a4f 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -272,8 +272,11 @@ static void evlist__check_cpu_maps(struct evlist *evlist)
 		}
 
 		for_each_group_evsel(pos, leader) {
-			evsel__set_leader(pos, pos);
-			pos->core.nr_members = 0;
+			if (!evsel__must_be_in_group(pos) && pos != leader) {
+				evsel__set_leader(pos, pos);
+				pos->core.nr_members = 0;
+				leader->core.nr_members--;
+			}
 		}
 		evsel->core.leader->nr_members = 0;
 	}
-- 
2.35.1