#+TITLE: Performance-Aware Programming
#+AUTHOR: Casey Muratori


* Definition
  Just knowing what you're doing can affect performance
  Not doing actual low level performance optimization for specific hardware

  "If you understand CSS you should understand this"

* Thinking about the CPU

If you think of a processor as a box which takes instructions as inputs
and then they do some work before producing the output, you have two
levers to pull for performance.

1. Reduce the # of instructions
   Simplify the program or generally reduce the work that the CPU needs
2. Speed of the Instruction
   Change the set of instructions you're passing through the CPU based
   on how much time it might take to process.

* Prologue

In a simple python program below: We achieve ~0.006 adds/cycle

#+begin_src python
  def add(a, b):
      a + b

  c = 1234 + 5678
#+end_src


In the naive C version we're looking at ~0.8 adds/cycle

If we get smarter and do some optimization with SIMD we can achive up to 16 adds/cycle.