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#include <iostream>
#include <cstdlib>
#include <cstdint>
#include "parallel.h"
#ifndef __Complex_h__
#include <complex>
typedef std::complex<double> Complex;
#endif
#include "statistics.h"
#include "align.h"
#include <chrono>
namespace utils {
int ALIGNMENT=2*sizeof(Complex); // Must be a multiple of sizeof(Complex)
}
using namespace utils;
size_t threshold=SIZE_MAX;
namespace parallel {
size_t lastThreads=SIZE_MAX;
const size_t maxThreshold=1 << 24;
size_t parallelLoop(Complex *A, size_t m, size_t threads)
{
auto T0=std::chrono::steady_clock::now();
PARALLEL(
for(size_t k=0; k < m; ++k)
A[k]=k;
);
PARALLEL(
for(size_t k=0; k < m; ++k)
A[k] *= k;
);
auto T1=std::chrono::steady_clock::now();
auto elapsed=std::chrono::duration_cast<std::chrono::nanoseconds>
(T1-T0);
return elapsed.count();
}
size_t measureThreshold(size_t threads)
{
if(threads > 1) {
for(size_t m=1; m < maxThreshold; m *= 2) {
Complex *A=ComplexAlign(m);
if(!A)
break;
if(parallelLoop(A,m,threads) < parallelLoop(A,m,1))
return m;
deleteAlign(A);
}
}
return maxThreshold;
}
void Threshold(size_t threads)
{
if(threads > 1 && threads < lastThreads) {
statistics S(true);
for(size_t i=0; i < 10; ++i)
S.add(measureThreshold(threads));
threshold=S.median();
lastThreads=threads;
}
}
}
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