[PATCH v3] perf stat: Disable NMI watchdog message on hybrid

[Jin Yao]

If we run a single workload that only runs on big core, there is always a
ugly message about disabling the NMI watchdog because the atom is not
counted.

Before:

  # ./perf stat true

   Performance counter stats for 'true':

                0.43 msec task-clock                #    0.396 CPUs utilized
                   0      context-switches          #    0.000 /sec
                   0      cpu-migrations            #    0.000 /sec
                  45      page-faults               #  103.918 K/sec
             639,634      cpu_core/cycles/          #    1.477 G/sec
       <not counted>      cpu_atom/cycles/                                              (0.00%)
             643,498      cpu_core/instructions/    #    1.486 G/sec
       <not counted>      cpu_atom/instructions/                                        (0.00%)
             123,715      cpu_core/branches/        #  285.694 M/sec
       <not counted>      cpu_atom/branches/                                            (0.00%)
               4,094      cpu_core/branch-misses/   #    9.454 M/sec
       <not counted>      cpu_atom/branch-misses/                                       (0.00%)

         0.001092407 seconds time elapsed

         0.001144000 seconds user
         0.000000000 seconds sys

  Some events weren't counted. Try disabling the NMI watchdog:
          echo 0 > /proc/sys/kernel/nmi_watchdog
          perf stat ...
          echo 1 > /proc/sys/kernel/nmi_watchdog

  # ./perf stat -e '{cpu_atom/cycles/,msr/tsc/}' true

   Performance counter stats for 'true':

       <not counted>      cpu_atom/cycles/                                              (0.00%)
       <not counted>      msr/tsc/                                                      (0.00%)

         0.001904106 seconds time elapsed

         0.001947000 seconds user
         0.000000000 seconds sys

  Some events weren't counted. Try disabling the NMI watchdog:
          echo 0 > /proc/sys/kernel/nmi_watchdog
          perf stat ...
          echo 1 > /proc/sys/kernel/nmi_watchdog
  The events in group usually have to be from the same PMU. Try reorganizing the group.

Now we disable the NMI watchdog message on hybrid, otherwise there
are too many false positives.

After:

  # ./perf stat true

   Performance counter stats for 'true':

                0.79 msec task-clock                #    0.419 CPUs utilized
                   0      context-switches          #    0.000 /sec
                   0      cpu-migrations            #    0.000 /sec
                  48      page-faults               #   60.889 K/sec
             777,692      cpu_core/cycles/          #  986.519 M/sec
       <not counted>      cpu_atom/cycles/                                              (0.00%)
             669,147      cpu_core/instructions/    #  848.828 M/sec
       <not counted>      cpu_atom/instructions/                                        (0.00%)
             128,635      cpu_core/branches/        #  163.176 M/sec
       <not counted>      cpu_atom/branches/                                            (0.00%)
               4,089      cpu_core/branch-misses/   #    5.187 M/sec
       <not counted>      cpu_atom/branch-misses/                                       (0.00%)

         0.001880649 seconds time elapsed

         0.001935000 seconds user
         0.000000000 seconds sys

  # ./perf stat -e '{cpu_atom/cycles/,msr/tsc/}' true

   Performance counter stats for 'true':

       <not counted>      cpu_atom/cycles/                                              (0.00%)
       <not counted>      msr/tsc/                                                      (0.00%)

         0.000963319 seconds time elapsed

         0.000999000 seconds user
         0.000000000 seconds sys

Signed-off-by: Jin Yao <yao.jin@xxxxxxxxxxxxxxx>
---
v3:
 - Use evlist__has_hybrid() to check there is at least one hybrid
   event in evlist.

v2:
 - If the group was mixed with hybrid event and non-hybrid event,
   the NMI watchdog message was still reported. V2 adds checking
   for hybrid event mixed group.

 tools/perf/util/stat-display.c | 9 ++++++---
 1 file changed, 6 insertions(+), 3 deletions(-)

diff --git a/tools/perf/util/stat-display.c b/tools/perf/util/stat-display.c
index b759dfd633b4..55ae0d1705a9 100644
--- a/tools/perf/util/stat-display.c
+++ b/tools/perf/util/stat-display.c
@@ -19,6 +19,7 @@
 #include "util.h"
 #include "iostat.h"
 #include "pmu-hybrid.h"
+#include "evlist-hybrid.h"
 
 #define CNTR_NOT_SUPPORTED	"<not supported>"
 #define CNTR_NOT_COUNTED	"<not counted>"
@@ -465,9 +466,11 @@ static void printout(struct perf_stat_config *config, struct aggr_cpu_id id, int
 			config->csv_sep);
 
 		if (counter->supported) {
-			config->print_free_counters_hint = 1;
-			if (is_mixed_hw_group(counter))
-				config->print_mixed_hw_group_error = 1;
+			if (!evlist__has_hybrid(counter->evlist)) {
+				config->print_free_counters_hint = 1;
+				if (is_mixed_hw_group(counter))
+					config->print_mixed_hw_group_error = 1;
+			}
 		}
 
 		fprintf(config->output, "%-*s%s",
-- 
2.17.1