История изменений

Исправление invy, 27.10.15 13:22 (текущая версия) :

оптимизация 1:

#include <stdlib.h>
#include <vector>

struct Ball {
  float x;
  float y;
  float dir_x;
  float dir_y;
};

struct BallsManager
{
  BallsManager(size_t count);
  void process();

  size_t m_count;
  std::vector<Ball> balls;
};


BallsManager::BallsManager(size_t count):
	m_count(count), balls(count)
{
  for (size_t i = 0; i < m_count; ++i) {
    balls[i].x = (i % 200) + 5.0f;
    balls[i].dir_x = 1.0f;
    balls[i].y = (i % 200) + 5.0f;
    balls[i].dir_y = 1.0f;
  }
}


void BallsManager::process()
{
  static const float min_x = 0.0f;
  static const float max_x = 640.0f;
  static const float min_y = 0.0f;
  static const float max_y = 480.0f;

  for (Ball &ball : balls)
  {
    if (ball.x <= min_x || ball.x >= max_x)
       ball.dir_x *= -1;
    ball.x += ball.dir_x;

    if (ball.y <= min_y || ball.y >= max_y)
       ball.dir_y *= -1;
    ball.y += ball.dir_y;
  }
}

оптимизация 2:

#include <stdlib.h>
#include <vector>

struct Ball {
  int x;
  int y;
  int dir_x;
  int dir_y;
};

struct BallsManager
{
  BallsManager(size_t count);
  void process();

  size_t m_count;
  std::vector<Ball> balls;
};


BallsManager::BallsManager(size_t count):
	m_count(count), balls(count)
{
  for (size_t i = 0; i < m_count; ++i) {
    balls[i].x = ((i % 200) + 5) * 100;
    balls[i].dir_x = 100;
    balls[i].y = ((i % 200) + 5) * 100;
    balls[i].dir_y = 100;
  }
}


void BallsManager::process()
{
  static const int min_x = 0;
  static const int max_x = 64000;
  static const int min_y = 0;
  static const int max_y = 48000;

  for (Ball &ball : balls)
  {
    if (ball.x <= min_x || ball.x >= max_x)
       ball.dir_x *= -1;
    ball.x += ball.dir_x;

    if (ball.y <= min_y || ball.y >= max_y)
       ball.dir_y *= -1;
    ball.y += ball.dir_y;
  }
}

венда, MSVS, с опцией /O2
100 000 итераций

$ time opt2.exe
real    0m3.373s
user    0m0.015s
sys     0m0.046s

$ time opt1.exe
real    0m4.248s
user    0m0.031s
sys     0m0.015s

$ time orig.exe
real    0m8.663s
user    0m0.031s
sys     0m0.015s

Исправление invy, 27.10.15 13:20:

оптимизация 1:

#include <stdlib.h>
#include <vector>

struct Ball {
  float x;
  float y;
  float dir_x;
  float dir_y;
};

struct BallsManager
{
  BallsManager(size_t count);
  void process();

  size_t m_count;
  std::vector<Ball> balls;
};


BallsManager::BallsManager(size_t count):
	m_count(count), balls(count)
{
  for (size_t i = 0; i < m_count; ++i) {
    balls[i].x = (i % 200) + 5.0f;
    balls[i].dir_x = 1.0f;
    balls[i].y = (i % 200) + 5.0f;
    balls[i].dir_y = 1.0f;
  }
}


void BallsManager::process()
{
  static const float min_x = 0.0f;
  static const float max_x = 640.0f;
  static const float min_y = 0.0f;
  static const float max_y = 480.0f;

  for (Ball &ball : balls)
  {
    if (ball.x <= min_x || ball.x >= max_x)
       ball.dir_x *= -1;
    ball.x += ball.dir_x;

    if (ball.y <= min_y || ball.y >= max_y)
       ball.dir_y *= -1;
    ball.y += ball.dir_y;
  }
}

оптимизация 2:

#include <stdlib.h>
#include <vector>

struct Ball {
  int x;
  int y;
  int dir_x;
  int dir_y;
};

struct BallsManager
{
  BallsManager(size_t count);
  void process();

  size_t m_count;
  std::vector<Ball> balls;
};


BallsManager::BallsManager(size_t count):
	m_count(count), balls(count)
{
  for (size_t i = 0; i < m_count; ++i) {
    balls[i].x = ((i % 200) + 5.0) * 100;
    balls[i].dir_x = 100;
    balls[i].y = ((i % 200) + 5.0) * 100;
    balls[i].dir_y = 100;
  }
}


void BallsManager::process()
{
  static const int min_x = 0;
  static const int max_x = 64000;
  static const int min_y = 0;
  static const int max_y = 48000;

  for (Ball &ball : balls)
  {
    if (ball.x <= min_x || ball.x >= max_x)
       ball.dir_x *= -1;
    ball.x += ball.dir_x;

    if (ball.y <= min_y || ball.y >= max_y)
       ball.dir_y *= -1;
    ball.y += ball.dir_y;
  }
}

венда, MSVS, с опцией /O2
100 000 итераций

$ time opt2.exe
real    0m3.373s
user    0m0.015s
sys     0m0.046s

$ time opt1.exe
real    0m4.248s
user    0m0.031s
sys     0m0.015s

$ time orig.exe
real    0m8.663s
user    0m0.031s
sys     0m0.015s

Исходная версия invy, 27.10.15 13:19:

оптимизация 1:

#include <stdlib.h>
#include <vector>

struct Ball {
  float x;
  float y;
  float dir_x;
  float dir_y;
};

struct BallsManager
{
  BallsManager(size_t count);
  void process();

  size_t m_count;
  std::vector<Ball> balls;
};


BallsManager::BallsManager(size_t count):
	m_count(count), balls(count)
{
  for (size_t i = 0; i < m_count; ++i) {
    balls[i].x = (i % 200) + 5.0f;
    balls[i].dir_x = 1.0f;
    balls[i].y = (i % 200) + 5.0f;
    balls[i].dir_y = 1.0f;
  }
}


void BallsManager::process()
{
  static const float min_x = 0.0f;
  static const float max_x = 640.0f;
  static const float min_y = 0.0f;
  static const float max_y = 480.0f;

  for (Ball &ball : balls)
  {
    if (ball.x <= min_x || ball.x >= max_x)
       ball.dir_x *= -1;
    ball.x += ball.dir_x;

    if (ball.y <= min_y || ball.y >= max_y)
       ball.dir_y *= -1;
    ball.y += ball.dir_y;
  }
}

оптимизация 2:

#include <stdlib.h>
#include <vector>

struct Ball {
  int x;
  int y;
  int dir_x;
  int dir_y;
};

struct BallsManager
{
  BallsManager(size_t count);
  void process();

  size_t m_count;
  std::vector<Ball> balls;
};


BallsManager::BallsManager(size_t count):
	m_count(count), balls(count)
{
  for (size_t i = 0; i < m_count; ++i) {
    balls[i].x = (i % 200) + 5.0f;
    balls[i].dir_x = 1.0f;
    balls[i].y = (i % 200) + 5.0f;
    balls[i].dir_y = 1.0f;
  }
}


void BallsManager::process()
{
  static const int min_x = 0;
  static const int max_x = 64000;
  static const int min_y = 0;
  static const int max_y = 48000;

  for (Ball &ball : balls)
  {
    if (ball.x <= min_x || ball.x >= max_x)
       ball.dir_x *= -1;
    ball.x += ball.dir_x;

    if (ball.y <= min_y || ball.y >= max_y)
       ball.dir_y *= -1;
    ball.y += ball.dir_y;
  }
}

венда, MSVS, с опцией /O2
100 000 итераций

$ time opt2.exe
real    0m3.373s
user    0m0.015s
sys     0m0.046s

$ time opt1.exe
real    0m4.248s
user    0m0.031s
sys     0m0.015s

$ time orig.exe
real    0m8.663s
user    0m0.031s
sys     0m0.015s