task8

ex3/seq/thread_17/main.cpp

@@ -0,0 +1,84 @@
+// C++ Vorlesung  xxx
+// C++-17: Threads, execution policies
+//   Great web pages, great book by Filipek:   https://www.bfilipek.com/2018/06/parstl-tests.html
+
+/*
+ g++ -O3 -std=c++17 main.cpp -ltbb
+ g++ -O3 -std=c++17 -pedantic -Weffc++ -Wall -Wextra -pedantic -Wswitch-default -Wfloat-equal -Wundef -Wredundant-decls -Winit-self -Wshadow -Wparentheses -Wshadow -Wunreachable-code -Wuninitialized -Wmaybe-uninitialized main.cpp -ltbb
+ ---
+ cppcheck --enable=all --inconclusive --std=c++11 --std=posix --suppress=missingIncludeSystem main.cpp
+ clang++ -O3 -std=c++17 -ltbb main.cpp
+ clang++ -std=c++17 -fsyntax-only -Wdocumentation -Wconversion -Wshadow -Wfloat-conversion -pedantic main.cpp
+ clang++ -std=c++17 -Weverything -Wno-c++98-compat -Wno-padded -ltbb main.cpp
+ clang++ -cc1 --help
+ ---
+ icpc -O3 -std=c++17 -ltbb -Wall -Wextra -pedantic main.cpp
+*/
+
+#include <algorithm>
+#include <chrono>
+#include <execution>          // execution policy
+#include <iostream>
+#include <numeric>            //  accumulate
+#include <random>
+#include <vector>
+using namespace std;
+using namespace std::chrono;  // timing
+
+// Great web pages, great book by Filipek
+// https://www.bfilipek.com/2018/06/parstl-tests.html
+template <typename TFunc> void RunAndMeasure(const char *title, TFunc func)
+{
+    const auto start = std::chrono::steady_clock::now();
+    auto ret = func();
+    const auto end = std::chrono::steady_clock::now();
+    std::cout << title << ": " <<
+              std::chrono::duration <double, std::milli>(end - start).count()
+              << " ms, res " << ret << "\n";
+}
+
+int main()
+{
+    //std::vector<double> v(6000000, 0.5);
+    std::vector<double> v(1<<30, 0.5);
+
+    RunAndMeasure("std::warm up", [&v]
+    {
+        return std::reduce(std::execution::seq, v.begin(), v.end(), 0.0);
+    });
+
+    RunAndMeasure("std::accumulate", [&v]
+    {
+        return std::accumulate(v.begin(), v.end(), 0.0);
+    });
+
+    RunAndMeasure("std::reduce, seq", [&v]
+    {
+        return std::reduce(std::execution::seq, v.begin(), v.end(), 0.0);
+    });
+
+    RunAndMeasure("std::reduce, par", [&v]
+    {
+        return std::reduce(std::execution::par, v.begin(), v.end(), 0.0);
+    });
+
+    RunAndMeasure("std::reduce, par_unseq", [&v]
+    {
+        return std::reduce(std::execution::par_unseq, v.begin(), v.end(), 0.0);
+    });
+
+    RunAndMeasure("std::find, seq", [&v]
+    {
+        auto res = std::find(std::execution::seq, std::begin(v), std::end(v), 0.6);
+        return res == std::end(v) ? 0.0 : 1.0;
+    });
+
+    RunAndMeasure("std::find, par", [&v]
+    {
+        auto res = std::find(std::execution::par, std::begin(v), std::end(v), 0.6);
+        return res == std::end(v) ? 0.0 : 1.0;
+    });
+
+    return 0;
+}
+