linux-kernel - [PATCH 05/11] perf stat: Check existence of frontend/backed stalled cycles

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Date:	Mon, 29 Feb 2016 16:22:01 -0300
From:	Arnaldo Carvalho de Melo <acme@...nel.org>
To:	Ingo Molnar <mingo@...nel.org>
Cc:	linux-kernel@...r.kernel.org, Andi Kleen <ak@...ux.intel.com>,
	Stephane Eranian <eranian@...gle.com>,
	Arnaldo Carvalho de Melo <acme@...hat.com>
Subject: [PATCH 05/11] perf stat: Check existence of frontend/backed stalled cycles

From: Andi Kleen <ak@...ux.intel.com>

Only put the frontend/backend stalled cycles into the default perf stat
events when the CPU actually supports them.

This avoids empty columns with --metric-only on newer Intel CPUs.

Committer note:

Before:

  $ perf stat ls
  a.patch

  Performance counter stats for 'ls':

         0.822067 task-clock (msec)   #   0.873 CPUs utilized   (82.26%)
                0 context-switches    #   0.000 K/sec           (82.26%)
                0 cpu-migrations      #   0.000 K/sec           (82.26%)
              125 page-faults         #   0.152 M/sec           (82.26%)
        2,516,127 cycles              #   3.061 GHz             (82.84%)
  <not supported> stalled-cycles-frontend
  <not supported> stalled-cycles-backend
        2,430,467 instructions        #   0.97  insn per cycle  (82.84%)
          486,235 branches            # 591.479 M/sec           (82.84%)
           18,389 branch-misses       #   3.78% of all branches (82.84%)

      0.000941536 seconds time elapsed
  $

After:

  $ perf stat ls
  a.patch

  Performance counter stats for 'ls':

         0.824919 task-clock (msec)   #   0.893 CPUs utilized   (85.47%)
                0 context-switches    #   0.000 K/sec           (85.47%)
                0 cpu-migrations      #   0.000 K/sec           (85.47%)
              124 page-faults         #   0.150 M/sec           (85.47%)
          2521790 cycles              #   3.057 GHz             (86.15%)
          2364913 instructions        #   0.94  insn per cycle  (86.15%)
           471970 branches            # 572.141 M/sec           (86.15%)
            16935 branch-misses       #   3.59% of all branches (86.15%)

      0.000923397 seconds time elapsed
  $

Signed-off-by: Andi Kleen <ak@...ux.intel.com>
Acked-by: Jiri Olsa <jolsa@...nel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@...hat.com>
Cc: Stephane Eranian <eranian@...gle.com>
Link: http://lkml.kernel.org/r/1456532881-26621-2-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@...hat.com>
---
 tools/perf/builtin-stat.c | 22 ++++++++++++++++++++--
 1 file changed, 20 insertions(+), 2 deletions(-)

diff --git a/tools/perf/builtin-stat.c b/tools/perf/builtin-stat.c
index 8c0bc0fe5179..24f222dd2a8a 100644
--- a/tools/perf/builtin-stat.c
+++ b/tools/perf/builtin-stat.c
@@ -1441,7 +1441,7 @@ static int perf_stat_init_aggr_mode_file(struct perf_stat *st)
  */
 static int add_default_attributes(void)
 {
-	struct perf_event_attr default_attrs[] = {
+	struct perf_event_attr default_attrs0[] = {
 
   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_TASK_CLOCK		},
   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_CONTEXT_SWITCHES	},
@@ -1449,8 +1449,14 @@ static int add_default_attributes(void)
   { .type = PERF_TYPE_SOFTWARE, .config = PERF_COUNT_SW_PAGE_FAULTS		},
 
   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_CPU_CYCLES		},
+};
+	struct perf_event_attr frontend_attrs[] = {
   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_FRONTEND	},
+};
+	struct perf_event_attr backend_attrs[] = {
   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_STALLED_CYCLES_BACKEND	},
+};
+	struct perf_event_attr default_attrs1[] = {
   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_INSTRUCTIONS		},
   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_INSTRUCTIONS	},
   { .type = PERF_TYPE_HARDWARE, .config = PERF_COUNT_HW_BRANCH_MISSES		},
@@ -1567,7 +1573,19 @@ static int add_default_attributes(void)
 	}
 
 	if (!evsel_list->nr_entries) {
-		if (perf_evlist__add_default_attrs(evsel_list, default_attrs) < 0)
+		if (perf_evlist__add_default_attrs(evsel_list, default_attrs0) < 0)
+			return -1;
+		if (pmu_have_event("cpu", "stalled-cycles-frontend")) {
+			if (perf_evlist__add_default_attrs(evsel_list,
+						frontend_attrs) < 0)
+				return -1;
+		}
+		if (pmu_have_event("cpu", "stalled-cycles-backend")) {
+			if (perf_evlist__add_default_attrs(evsel_list,
+						backend_attrs) < 0)
+				return -1;
+		}
+		if (perf_evlist__add_default_attrs(evsel_list, default_attrs1) < 0)
 			return -1;
 	}
 
-- 
2.5.0