• Emil Persson @Humus
  • Blog
  • <2013> Low-Level Thinking in High-Level Shading Languages
  • <2014> Low-Level Shader Optimization for Next-Gen and DX11
  • <2018> Rule of optimization
• Matt Pettineo @mynameismjp

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

float rand(float n){return fract(sin(n) * 43758.5453123);}

float noise(float p){
	float fl = floor(p);
  float fc = fract(p);
	return mix(rand(fl), rand(fl + 1.0), fc);
}