Print mean/stddev of the # of iterations.
diff --git a/src/benchmark.cc b/src/benchmark.cc
index 5a8e023..e06567b 100644
--- a/src/benchmark.cc
+++ b/src/benchmark.cc
@@ -12,6 +12,8 @@
// See the License for the specific language governing permissions and
// limitations under the License.
+#include <algorithm>
+
#include "benchmark/benchmark.h"
#include "benchmark/macros.h"
#include "colorprint.h"
@@ -258,11 +260,15 @@
Stat1MinMax_d(it->max_heapbytes_used, it->iterations);
}
- // Get the data from the accumulator to BenchmarkRunData's.
+ // Get the data from the accumulator to BenchmarkRunData's. In the
+ // computations below we must multiply by the number of iterations since
+ // PrintRunData will divide by it.
mean_data->benchmark_name = reports[0].benchmark_name + "_mean";
- mean_data->iterations = real_accumulated_time_stat.numSamples();
- mean_data->real_accumulated_time = real_accumulated_time_stat.sum();
- mean_data->cpu_accumulated_time = cpu_accumulated_time_stat.sum();
+ mean_data->iterations = iterations_stat.Mean();
+ mean_data->real_accumulated_time = real_accumulated_time_stat.Mean() *
+ mean_data->iterations;
+ mean_data->cpu_accumulated_time = cpu_accumulated_time_stat.Mean() *
+ mean_data->iterations;
mean_data->bytes_per_second = bytes_per_second_stat.Mean();
mean_data->items_per_second = items_per_second_stat.Mean();
mean_data->max_heapbytes_used = max_heapbytes_used_stat.max();
@@ -278,9 +284,17 @@
stddev_data->benchmark_name = reports[0].benchmark_name + "_stddev";
stddev_data->report_label = mean_data->report_label;
- stddev_data->iterations = real_accumulated_time_stat.numSamples();
- // We multiply by the number of iterations since PrintRunData expects a total
- // time.
+ stddev_data->iterations = iterations_stat.StdDev();
+ // Ugly hack here! iterations_stat.StdDev() above may be 0 if all the
+ // repetitions have the same number of iterations. Blindly multiplying by 0
+ // in the computation of real/cpu_accumulated_time below would lead to 0/0 in
+ // PrintRunData. To avoid this, we set the number of iterations to something
+ // negative here, and PrintRunData prints it as 0 (see the std::max there).
+ // Thus the stddev of both the number of iterations and the times are printed
+ // correctly.
+ if (stddev_data->iterations == 0) {
+ stddev_data->iterations = -1;
+ }
stddev_data->real_accumulated_time = real_accumulated_time_stat.StdDev() *
stddev_data->iterations;
stddev_data->cpu_accumulated_time = cpu_accumulated_time_stat.StdDev() *
@@ -473,7 +487,8 @@
(static_cast<double>(result.iterations)),
(result.cpu_accumulated_time * 1e9) /
(static_cast<double>(result.iterations)));
- ColorPrintf(COLOR_CYAN, "%10lld", result.iterations);
+ // See ComputeStats for why a negative value is printed as 0.
+ ColorPrintf(COLOR_CYAN, "%10lld", std::max(0LL, result.iterations));
ColorPrintf(COLOR_DEFAULT, "%*s %*s %s %s\n",
13, rate.c_str(),
18, items.c_str(),
