measure + para auf dev branch von Kai

parallel/parallel_measurements.cpp

@@ -0,0 +1,83 @@
+
+#include <iostream>
+#include <fstream>
+#include <vector>
+#include <thread>
+#include <chrono>
+#include <string>
+
+void readFile(const std::string& filename, std::vector<int>& data) {
+    std::ifstream file(filename);
+    if (!file) {
+        std::cerr << "Fehler: Datei '" << filename << "' konnte nicht geöffnet werden!\n";
+        return;
+    }
+    int v;
+    while (file >> v) data.push_back(v);
+}
+
+int countIncreasesSerial(const std::vector<int>& data) {
+    if (data.size() < 2) return 0;
+    int increases = 0;
+    for (size_t i = 1; i < data.size(); ++i)
+        if (data[i] > data[i - 1]) ++increases;
+    return increases;
+}
+
+int countIncreasesParallel(const std::vector<int>& messungen, int numThreads = 4) {
+    int totalComparisons = static_cast<int>(messungen.size()) - 1;
+    if (totalComparisons <= 0) return 0;
+
+    std::vector<int> results(numThreads, 0);
+    std::vector<std::thread> threads;
+    threads.reserve(numThreads);
+
+    int base = totalComparisons / numThreads;
+    int remainder  = totalComparisons % numThreads;
+
+    int idx = 1;
+    for (int t = 0; t < numThreads; t++) {
+        int startIdx = idx;
+        int count = base + (t < remainder ? 1 : 0);
+        int endIdx = idx + count - 1;
+        idx = endIdx + 1;
+
+        if (count <= 0) {
+            results[t] = 0;
+            continue;
+        }
+
+        threads.emplace_back([&, t, startIdx, endIdx]() {
+            int localCount = 0;
+            for (int i = startIdx; i <= endIdx; ++i)
+                if (messungen[i] > messungen[i - 1])
+                    ++localCount;
+            results[t] = localCount;
+        });
+    }
+
+    for (auto& th : threads) th.join();
+
+    int total = 0;
+    for (int r : results) total += r;
+    return total;
+}
+
+int main() {
+    std::vector<int> messungen;
+    readFile("parallel/measurements.txt", messungen);
+    std::cout << "Gelesene Werte: " << messungen.size() << "\n";
+
+    auto t0 = std::chrono::steady_clock::now();
+    int s = countIncreasesSerial(messungen);
+    auto t1 = std::chrono::steady_clock::now();
+
+    auto p0 = std::chrono::steady_clock::now();
+    int p = countIncreasesParallel(messungen, 4);
+    auto p1 = std::chrono::steady_clock::now();
+
+    std::cout << "Seriell:   " << s << "  Dauer: " << std::chrono::duration<double>(t1 - t0).count() << "s\n";
+    std::cout << "Parallel:  " << p << "  Dauer: " << std::chrono::duration<double>(p1 - p0).count() << "s\n";
+
+    return 0;
+}