perf stat: Check existence of frontend/backed stalled cycles

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

    Performance counter stats for 'ls':

          1.080893     task-clock (msec)      #    0.619 CPUs utilized
                 0     context-switches       #    0.000 K/sec
                 0     cpu-migrations         #    0.000 K/sec
                97     page-faults            #    0.090 M/sec
         3,327,741     cycles                 #    3.079 GHz
   <not supported>     stalled-cycles-frontend
   <not supported>     stalled-cycles-backend
         1,609,544     instructions           #    0.48  insn per cycle
           319,117     branches               #  295.235 M/sec
            12,246     branch-misses          #    3.84% of all branches

       0.001746508 seconds time elapsed
  $

After:

  $ perf stat ls

    Performance counter stats for 'ls':

          0.693948     task-clock (msec)      #    0.662 CPUs utilized
                 0     context-switches       #    0.000 K/sec
                 0     cpu-migrations         #    0.000 K/sec
                95     page-faults            #    0.137 M/sec
         1,792,509     cycles                 #    2.583 GHz
         1,599,047     instructions           #    0.89  insn per cycle
           316,328     branches               #  455.838 M/sec
            12,453     branch-misses          #    3.94% of all branches

       0.001048987 seconds time elapsed
  $

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Tested-by: Arnaldo Carvalho de Melo <acme@redhat.com>
Cc: Stephane Eranian <eranian@google.com>
Link: http://lkml.kernel.org/r/1456532881-26621-2-git-send-email-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files 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;
         }