69 lines
2.2 KiB
C++
69 lines
2.2 KiB
C++
// HOW TO COMPILE ON MAC (paste these lines in terminal):
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// export CPPFLAGS="-I/opt/homebrew/opt/libomp/include"
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// export LDFLAGS="-L/opt/homebrew/opt/libomp/lib"
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// clang++ -std=c++17 -O3 -Xpreprocessor -fopenmp $CPPFLAGS mainEx6.cpp bench_funcs.cpp $LDFLAGS -lomp -o Ex6
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// ./Ex6
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//
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// You can set OMP_NUM_THREADS in the shell to control threads.
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#include <iostream>
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#include <vector>
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#include <chrono>
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#include <omp.h>
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#include "bench_funcs.h"
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using namespace std;
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using namespace std::chrono;
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int main()
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{
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size_t n = 200000;
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size_t maxit = 5000;
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double omega = 1.0;
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double tol = 1e-8;
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// show threads
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#pragma omp parallel
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{
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#pragma omp single
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cout << "Using " << omp_get_num_threads() << " OpenMP threads\n";
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}
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CSR K_atomic, K_noatom;
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vector<double> f;
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cout << "\n--- Build with ATOMICS (parallel over elements with atomic adds) ---\n";
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auto t0 = high_resolution_clock::now();
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build_fem_system_atomic(n, K_atomic, f);
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auto t1 = high_resolution_clock::now();
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cout << "Assembly (atomic) time = " << duration<double>(t1 - t0).count() << " s\n";
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cout << "\nBuild with NO ATOMICS (grouped / per-row accumulation)\n";
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t0 = high_resolution_clock::now();
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build_fem_system_no_atomic(n, K_noatom, f);
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t1 = high_resolution_clock::now();
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cout << "Assembly (no-atomic) time = " << duration<double>(t1 - t0).count() << " s\n";
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// quick check: compare val arrays (they should be equal)
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bool same = true;
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if (K_atomic.val.size() == K_noatom.val.size()) {
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for (size_t i = 0; i < K_atomic.val.size(); ++i) {
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if (std::abs(K_atomic.val[i] - K_noatom.val[i]) > 1e-12) { //it was Fabs, changed it to abs
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same = false; break;
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}
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}
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} else same = false;
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cout << "\nMatrix equality check (atomic vs no-atomic): " << (same ? "OK" : "DIFFER") << "\n";
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// Run Jacobi solver on the no-atomic assembled matrix
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cout << "\nRun Jacobi on NO-ATOMIC matrix\n";
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vector<double> u;
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t0 = high_resolution_clock::now();
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jacobi_csr_parallel(K_noatom, f, u, maxit, omega, tol);
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t1 = high_resolution_clock::now();
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cout << "Jacobi time = " << duration<double>(t1 - t0).count() << " s\n";
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cout << "\nDone.\n";
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return 0;
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}
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