Nishanth Shanmugham nishanths

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

tmux cheat sheet

(C-x means ctrl+x, M-x means alt+x)

Prefix key

The default prefix is C-b. If you (or your muscle memory) prefer C-a, you need to add this to ~/.tmux.conf:

remap prefix to Control + a

To add Settings.bundle in Xcode. Command N and in Resource, choose Settings Bundle .
Open Root.plist in source code, paste the code below to replace it,

<?xml version="1.0" encoding="UTF-8"?>
<!DOCTYPE plist PUBLIC "-//Apple//DTD PLIST 1.0//EN" "http://www.apple.com/DTDs/PropertyList-1.0.dtd">
<plist version="1.0">
<dict>
	<key>PreferenceSpecifiers</key>

The fastest remote directory rsync over ssh archival I can muster (40MB/s over 1gb NICs)

This creates an archive that does the following:

rsync (Everyone seems to like -z, but it is much slower for me)

a: archive mode - rescursive, preserves owner, preserves permissions, preserves modification times, preserves group, copies symlinks as symlinks, preserves device files.
H: preserves hard-links
A: preserves ACLs

OS X Screencast to animated GIF

This gist shows how to create a GIF screencast using only free OS X tools: QuickTime, ffmpeg, and gifsicle.

Instructions

To capture the video (filesize: 19MB), using the free "QuickTime Player" application:

	0 => 000000
	1 => cd0000
	2 => 00cd00
	3 => cdcd00
	4 => 0000cd
	5 => cd00cd
	6 => 00cdcd
	7 => e5e5e5
	8 => 4d4d4d
	9 => ff0000

	# 0 is too far from ` ;)
	set -g base-index 1

	# Automatically set window title
	set-window-option -g automatic-rename on
	set-option -g set-titles on

	#set -g default-terminal screen-256color
	set -g status-keys vi
	set -g history-limit 10000

	// http://paulirish.com/2011/requestanimationframe-for-smart-animating/
	// http://my.opera.com/emoller/blog/2011/12/20/requestanimationframe-for-smart-er-animating

	// requestAnimationFrame polyfill by Erik Möller. fixes from Paul Irish and Tino Zijdel

	// MIT license

	(function() {
	var lastTime = 0;
	var vendors = ['ms', 'moz', 'webkit', 'o'];

	# Mac OS X Lion introduced a new, iOS-like context menu when you press and hold a key
	# that enables you to choose a character from a menu of options. If you are on Lion
	# try it by pressing and holding down 'e' in any app that uses the default NSTextField
	# for input.
	#
	# It's a nice feature and continues the blending of Mac OS X and iOS features. However,
	# it's a nightmare to deal with in Sublime Text if you're running Vintage (Vim) mode,
	# as it means you cannot press and hold h/j/k/l to move through your file. You have
	# to repeatedly press the keys to navigate.

	Latency Comparison Numbers (~2012)
	----------------------------------
	L1 cache reference 0.5 ns
	Branch mispredict 5 ns
	L2 cache reference 7 ns 14x L1 cache
	Mutex lock/unlock 25 ns
	Main memory reference 100 ns 20x L2 cache, 200x L1 cache
	Compress 1K bytes with Zippy 3,000 ns 3 us
	Send 1K bytes over 1 Gbps network 10,000 ns 10 us
	Read 4K randomly from SSD* 150,000 ns 150 us ~1GB/sec SSD