tools/perf/stat: Add event unit and scale support

This patch adds perf stat support for handling event units and
scales as exported by the kernel.

The kernel can export PMU events actual unit and scaling factor
via sysfs:

  $ ls -1 /sys/devices/power/events/energy-*
  /sys/devices/power/events/energy-cores
  /sys/devices/power/events/energy-cores.scale
  /sys/devices/power/events/energy-cores.unit
  /sys/devices/power/events/energy-pkg
  /sys/devices/power/events/energy-pkg.scale
  /sys/devices/power/events/energy-pkg.unit
  $ cat /sys/devices/power/events/energy-cores.scale
  2.3283064365386962890625e-10
  $ cat cat /sys/devices/power/events/energy-cores.unit
  Joules

This patch modifies the pmu event alias code to check
for the presence of the .unit and .scale files to load
the corresponding values. They are then used by perf stat
transparently:

   # perf stat -a -e power/energy-pkg/,power/energy-cores/,cycles -I 1000 sleep 1000
   #          time             counts   unit events
       1.000214717               3.07 Joules power/energy-pkg/         [100.00%]
       1.000214717               0.53 Joules power/energy-cores/
       1.000214717           12965028        cycles                    [100.00%]
       2.000749289               3.01 Joules power/energy-pkg/
       2.000749289               0.52 Joules power/energy-cores/
       2.000749289           15817043        cycles

When the event does not have an explicit unit exported by
the kernel, nothing is printed. In csv output mode, there
will be an empty field.

Special thanks to Jiri for providing the supporting code
in the parser to trigger reading of the scale and unit files.

Signed-off-by: Stephane Eranian <eranian@google.com>
Reviewed-by: Jiri Olsa <jolsa@redhat.com>
Reviewed-by: Andi Kleen <ak@linux.intel.com>
Signed-off-by: Peter Zijlstra <peterz@infradead.org>
Cc: zheng.z.yan@intel.com
Cc: bp@alien8.de
Cc: maria.n.dimakopoulou@gmail.com
Cc: acme@redhat.com
Link: http://lkml.kernel.org/r/1384275531-10892-3-git-send-email-eranian@google.com
Signed-off-by: Ingo Molnar <mingo@kernel.org>

1 files changed, 19 insertions, 9 deletions

diff --git a/tools/perf/util/parse-events.c b/tools/perf/util/parse-events.c
index 6de6f89c2a61..969cb8f0d88d 100644
--- a/tools/perf/util/parse-events.c
+++ b/tools/perf/util/parse-events.c
@@ -269,9 +269,10 @@ const char *event_type(int type)
 
 
 
-static int __add_event(struct list_head *list, int *idx,
-                       struct perf_event_attr *attr,
-                       char *name, struct cpu_map *cpus)
+static struct perf_evsel *
+__add_event(struct list_head *list, int *idx,
+            struct perf_event_attr *attr,
+            char *name, struct cpu_map *cpus)
 {
         struct perf_evsel *evsel;
 
@@ -279,19 +280,19 @@ static int __add_event(struct list_head *list, int *idx,
 
         evsel = perf_evsel__new_idx(attr, (*idx)++);
         if (!evsel)
-                return -ENOMEM;
+                return NULL;
 
         evsel->cpus = cpus;
         if (name)
                 evsel->name = strdup(name);
         list_add_tail(&evsel->node, list);
-        return 0;
+        return evsel;
 }
 
 static int add_event(struct list_head *list, int *idx,
                      struct perf_event_attr *attr, char *name)
 {
-        return __add_event(list, idx, attr, name, NULL);
+        return __add_event(list, idx, attr, name, NULL) ? 0 : -ENOMEM;
 }
 
 static int parse_aliases(char *str, const char *names[][PERF_EVSEL__MAX_ALIASES], int size)
@@ -633,6 +634,9 @@ int parse_events_add_pmu(struct list_head *list, int *idx,
 {
         struct perf_event_attr attr;
         struct perf_pmu *pmu;
+        struct perf_evsel *evsel;
+        char *unit;
+        double scale;
 
         pmu = perf_pmu__find(name);
         if (!pmu)
@@ -640,7 +644,7 @@ int parse_events_add_pmu(struct list_head *list, int *idx,
 
         memset(&attr, 0, sizeof(attr));
 
-        if (perf_pmu__check_alias(pmu, head_config))
+        if (perf_pmu__check_alias(pmu, head_config, &unit, &scale))
                 return -EINVAL;
 
         /*
@@ -652,8 +656,14 @@ int parse_events_add_pmu(struct list_head *list, int *idx,
         if (perf_pmu__config(pmu, &attr, head_config))
                 return -EINVAL;
 
-        return __add_event(list, idx, &attr, pmu_event_name(head_config),
-                           pmu->cpus);
+        evsel = __add_event(list, idx, &attr, pmu_event_name(head_config),
+                            pmu->cpus);
+        if (evsel) {
+                evsel->unit = unit;
+                evsel->scale = scale;
+        }
+
+        return evsel ? 0 : -ENOMEM;
 }
 
 int parse_events__modifier_group(struct list_head *list,