Daniel Agar dagar

Latency numbers every programmer should know

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

	#!/usr/bin/env python
	"""
	getimg.py

	Gets the current image of the day from NASA and sets it as the
	background in Gnome. The summary / description text is written
	to the image.

	Requires:
	PIL (apt-get install python-imaging or pip install PIL)