Data Locality: Particle System

particle_a.cpp

struct Particle {
	float x;
	float y;
	float z;
	float w;
	float vx;
	float vy;
	float vz;
	float vw;
}

struct A
{
	Particle *particles;
	int count;

	void update(float dt)
	{
		for (int i = 0; i<count; i++)
		{
			auto p = particles[i];
			p.x += p.vx * dt;
			p.y += p.vy * dt;
			p.z += p.vz * dt;
			p.w += p.vw * dt;
		}
	}
}

particle_b.cpp

struct Particle {
	float x;
	float y;
	float z;
	float w;
	float vx;
	float vy;
	float vz;
	float vw;
}

struct B
{
	Particle *particles;
	int count;

	void update(float dt)
	{
		parallel_for(0, count, [&](int i)
		{
			auto p = particles[i];
			p.x += p.vx * dt;
			p.y += p.vy * dt;
			p.z += p.vz * dt;
			p.w += p.vw * dt;
		});
	}
}