esaul

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns                     on recent CPU
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 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 4X memory

In Rails 3

NOTE: This post now lives (and kept up to date) on my blog: http://hakunin.com/rails3-load-paths

If you add a dir directly under app/

Do nothing. All files in this dir are eager loaded in production and lazy loaded in development by default.

If you add a dir under app/something/

Essential JavaScript Links

A curated list by Eric Elliott and friends. Suggest links in the comments below.

This is a very exclusive collection of only must-have JavaScript links. I'm only listing my favorite links. Nothing else makes the cut. Feel free to suggest links if you think they're good enough to make this list. The really curious should feel free to browse the comments to find other links. I can't guarantee the quality of links in the comments.

Full Disclosure

Some of these links are affiliate links, meaning that if you make a purchase, I might earn a little money. This has absolutely no bearing on whether or not links make the list. None, whatsoever. However, it does allow me more resources to fight poverty with code. Every little bit counts.

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:

Direct links to free Springer maths books (pdf versions)

duplicates = multiple editions

A Classical Introduction to Modern Number Theory,Kenneth IrelandMichael Rosen

A Course in Arithmetic,Jean-Pierre Serre

	package main

	import (
	"fmt"
	"http"
	"io/ioutil"
	"os"
	)

	func main() {

	#!/bin/sh

	# Some things taken from here
	# https://github.com/mathiasbynens/dotfiles/blob/master/.osx

	# Set the colours you can use
	black='\033[0;30m'
	white='\033[0;37m'
	red='\033[0;31m'
	green='\033[0;32m'

	#!/bin/sh

	# Alot of these configs have been taken from the various places
	# on the web, most from here
	# https://github.com/mathiasbynens/dotfiles/blob/master/.osx

	# Set the colours you can use
	black='\033[0;30m'
	white='\033[0;37m'
	red='\033[0;31m'