Created
July 19, 2015 19:34
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Test int vs float performance with simplest operations.
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#include "stdafx.h" | |
#define WIN32_LEAN_AND_MEAN | |
#include <Windows.h> | |
#include <array> | |
#include <vector> | |
#include <iostream> | |
#include <sstream> | |
#include <time.h> | |
std::ostringstream oss; | |
size_t tick() | |
{ | |
LARGE_INTEGER li; | |
::QueryPerformanceCounter(&li); | |
return (size_t&)li; | |
} | |
template<typename T> | |
size_t test_one(std::vector<T>& values) | |
{ | |
for (T& v : values) v = T(::rand()); | |
T sum = T(0); | |
size_t start = tick(); | |
for (auto v : values) sum += v; | |
//for (auto v : values) sum *= v; // halves win, floaters 60% slower than fixed | |
//for (auto v : values) sum += v; // halves win, floaters suck | |
// | |
// changes stuff diametrically, chars win, floaters are not left behind | |
//for (auto v : values) sum += v*values.front(); | |
size_t delta = tick() - start; | |
oss << sum; | |
return delta; | |
} | |
template<typename T> | |
void test(const char msg[], size_t loops, size_t count) | |
{ | |
std::vector<size_t> times(loops); | |
std::vector<T> values(count); | |
size_t avg = 0; | |
for (size_t& t: times) avg += t = test_one<T>(values); | |
for (size_t t : times) printf(" %i", t); | |
printf("|%s %i\n", msg, avg / loops); | |
} | |
void test_all(size_t loops, size_t count) | |
{ | |
test<char>("c", loops, count); | |
test<short>("h", loops, count); | |
test<unsigned short>("uh", loops, count); | |
test<int>("i", loops, count); | |
test<unsigned int>("ui", loops, count); | |
test<float>("f", loops, count); | |
test<double>("d", loops, count); | |
test<size_t>("s", loops, count); | |
} | |
void main() | |
{ | |
::srand((int)::time(nullptr)); | |
size_t loops = 10; | |
for (auto count : { 1000, 10*1000, 100 * 1000, 1000 * 1000 }) | |
{ | |
printf("\nTesting %i values %i times\n", count, loops); | |
test_all(loops, count); | |
} | |
printf("%i", oss.str().length()); | |
} | |
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