97 lines
2.9 KiB
C++
97 lines
2.9 KiB
C++
#include "mylib.h"
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#include <chrono> // timing
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#include <cstdlib> // atoi()
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#include <cstring> // strncmp()
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#include <iostream>
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#include <sstream>
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using namespace std;
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using namespace std::chrono; // timing
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int main(int argc, char **argv)
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{
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int const NLOOPS = 50; // chose a value such that the benchmark runs at least 10 sec.
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unsigned int N = 50000001;
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//##########################################################################
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// Read Paramater from command line (C++ style)
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cout << "Checking command line parameters for: -n <number> " << endl;
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for (int i = 1; i < argc; i++)
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{
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cout << " arg[" << i << "] = " << argv[i] << endl;
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if (std::strncmp(argv[i], "-n", 2) == 0 && i + 1 < argc) // found "-n" followed by another parameter
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{
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N = static_cast<unsigned int>(atoi(argv[i + 1]));
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}
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else
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{
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cout << "Corect call: " << argv[0] << " -n <number>\n";
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}
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}
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cout << "\nN = " << N << endl;
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//##########################################################################
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// Memory allocation
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cout << "Memory allocation\n";
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double *x, *y;
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x = new double [N];
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y = new double [N];
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cout.precision(2);
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cout << 2.0 * N *sizeof(x[0]) / 1024 / 1024 / 1024 << " GByte Memory allocated\n";
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cout.precision(6);
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//##########################################################################
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// Data initialization
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// Special: x_i = i+1; y_i = 1/x_i ==> <x,y> == N
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for (unsigned int i = 0; i < N; ++i)
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{
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x[i] = i + 1;
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y[i] = 1.0 / x[i];
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}
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//##########################################################################
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cout << "\nStart Benchmarking\n";
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auto tstart = system_clock::now(); // start timer
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// Do calculation
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double sk(0.0);
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for (int i = 0; i < NLOOPS; ++i)
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{
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sk = scalar(N, x, y);
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// sk = norm(N,x);
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}
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auto tend = system_clock::now(); // end timer
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auto duration = duration_cast<microseconds>(tend - tstart);
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auto t1 = static_cast<double>(duration.count()) / 1e6 ; // t1 in seconds
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t1 /= NLOOPS; // divide by number of function calls
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//##########################################################################
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// Check the correct result
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cout << "\n <x,y> = " << sk << endl;
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if (static_cast<unsigned int>(sk) != N)
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{
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cout << " !! W R O N G result !!\n";
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}
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cout << endl;
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//##########################################################################
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// Timings and Performance
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cout << endl;
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cout.precision(2);
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cout << "Timing in sec. : " << t1 << endl;
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cout << "GFLOPS : " << 2.0 * N / t1 / 1024 / 1024 / 1024 << endl;
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cout << "GiByte/s : " << 2.0 * N / t1 / 1024 / 1024 / 1024 * sizeof(x[0]) << endl;
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//##########################################################################
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// Free allocated memory
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delete [] y;
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delete [] x;
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return 0;
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}
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