[PATCH 09/13] perf stats: add max and min stats

[David Ahern <dsahern@gmail.com>]

Need an initialization function to set min to -1 to
differentiate from an actual min of 0.

Signed-off-by: David Ahern <dsahern@gmail.com>
Cc: Arnaldo Carvalho de Melo <acme@ghostprotocols.net>
Cc: Ingo Molnar <mingo@kernel.org>
Cc: Frederic Weisbecker <fweisbec@gmail.com>
Cc: Peter Zijlstra <peterz@infradead.org>
Cc: Jiri Olsa <jolsa@redhat.com>
Cc: Namhyung Kim <namhyung@kernel.org>
Cc: Xiao Guangrong <xiaoguangrong@linux.vnet.ibm.com>
---
 tools/perf/util/stat.c |    6 ++++++
 tools/perf/util/stat.h |    9 +++++++++
 2 files changed, 15 insertions(+)

diff --git a/tools/perf/util/stat.c b/tools/perf/util/stat.c
index 7c59c28..6506b3d 100644
--- a/tools/perf/util/stat.c
+++ b/tools/perf/util/stat.c
@@ -10,6 +10,12 @@ void update_stats(struct stats *stats, u64 val)
 	delta = val - stats->mean;
 	stats->mean += delta / stats->n;
 	stats->M2 += delta*(val - stats->mean);
+
+	if (val > stats->max)
+		stats->max = val;
+
+	if (val < stats->min)
+		stats->min = val;
 }
 
 double avg_stats(struct stats *stats)
diff --git a/tools/perf/util/stat.h b/tools/perf/util/stat.h
index 588367c..ae8ccd7 100644
--- a/tools/perf/util/stat.h
+++ b/tools/perf/util/stat.h
@@ -6,6 +6,7 @@
 struct stats
 {
 	double n, mean, M2;
+	u64 max, min;
 };
 
 void update_stats(struct stats *stats, u64 val);
@@ -13,4 +14,12 @@ double avg_stats(struct stats *stats);
 double stddev_stats(struct stats *stats);
 double rel_stddev_stats(double stddev, double avg);
 
+static inline void init_stats(struct stats *stats)
+{
+	stats->n    = 0.0;
+	stats->mean = 0.0;
+	stats->M2   = 0.0;
+	stats->min  = (u64) -1;
+	stats->max  = 0;
+}
 #endif
-- 
1.7.10.1