perf stat: Support duration_time for metrics

Some of the metrics formulas (like GFLOPs) need to know how long the
measurement period is. Support an internal event called duration_time,
which reports time in second. It maps to the dummy event, but is special
cased for statistics to report the walltime duration.

So far it is not printed, but only used internally for metrics.

Signed-off-by: Andi Kleen <ak@linux.intel.com>
Acked-by: Jiri Olsa <jolsa@kernel.org>
Link: http://lkml.kernel.org/r/20170831194036.30146-10-andi@firstfloor.org
Signed-off-by: Arnaldo Carvalho de Melo <acme@redhat.com>

1 files changed, 13 insertions, 4 deletions

diff --git a/tools/perf/util/stat-shadow.c b/tools/perf/util/stat-shadow.c
index 664f49a9b012..a2c12d1ef32a 100644
--- a/tools/perf/util/stat-shadow.c
+++ b/tools/perf/util/stat-shadow.c
@@ -641,11 +641,20 @@ static void generic_metric(const char *metric_expr,
         expr__add_id(&pctx, name, avg);
         for (i = 0; metric_events[i]; i++) {
                 struct saved_value *v;
+                struct stats *stats;
+                double scale;
 
-                v = saved_value_lookup(metric_events[i], cpu, false);
-                if (!v)
-                        break;
-                expr__add_id(&pctx, metric_events[i]->name, avg_stats(&v->stats));
+                if (!strcmp(metric_events[i]->name, "duration_time")) {
+                        stats = &walltime_nsecs_stats;
+                        scale = 1e-9;
+                } else {
+                        v = saved_value_lookup(metric_events[i], cpu, false);
+                        if (!v)
+                                break;
+                        stats = &v->stats;
+                        scale = 1.0;
+                }
+                expr__add_id(&pctx, metric_events[i]->name, avg_stats(stats)*scale);
         }
         if (!metric_events[i]) {
                 const char *p = metric_expr;