Merge pull request #318 from igchor/fix_mt

Fix mt benchmark compilation on windows

Author: lukaszstolarczuk

benchmark/multithread.cpp

@@ -84,7 +84,7 @@ static void mt_alloc_free(poolCreateExtParams params,
     std::cout << "mean: " << umf_bench::mean(values)
               << " [ms] std_dev: " << umf_bench::std_dev(values) << " [ms]"
               << " (total alloc failures: "
-              << std::accumulate(numFailures.begin(), numFailures.end(), 0)
+              << std::accumulate(numFailures.begin(), numFailures.end(), 0ULL)
               << " out of "
               << bench.n_iterations * bench.n_repeats * bench.n_threads << ")"
               << std::endl;

benchmark/multithread.hpp

@@ -144,11 +144,11 @@ template <typename T> double mean(const std::vector<T> &values) {
 
 template <typename T> double std_dev(const std::vector<T> &values) {
     auto m = mean(values);
-    std::vector<T> diff_squares;
+    std::vector<double> diff_squares;
     diff_squares.reserve(values.size());
 
     for (auto &v : values) {
-        diff_squares.push_back(std::pow((v - m), 2.0));
+        diff_squares.push_back((v - m) * (v - m));
     }
 
     return std::sqrt(mean(diff_squares));