Vignesh Shanmugam vigneshshanmugam

---------- Forwarded message ----------

From: Mark S. Miller <[email protected]>
Date: Tue, Nov 16, 2010 at 3:44 PM
Subject: "Future of Javascript" doc from our internal "JavaScript Summit"
last week
To: [email protected]

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

Quick, take a guess, what's the first hop latency to your home wireless router?

Below 1ms, right? Yeah, you wish!

Below are results from a quick test on my home router (Linksys E1550). Some lessons learned:

3-8ms median
very different latency tails on different channels (1,6,11)
running in mixed mode helps tame the long tails (do it, if you can)
all tests on 2.4Ghz, unfortunately E1550 can't do 5Ghz

How to set up stress-free SSL on an OS X development machine

One of the best ways to reduce complexity (read: stress) in web development is to minimize the differences between your development and production environments. After being frustrated by attempts to unify the approach to SSL on my local machine and in production, I searched for a workflow that would make the protocol invisible to me between all environments.

Most workflows make the following compromises:

Use HTTPS in production but HTTP locally. This is annoying because it makes the environments inconsistent, and the protocol choices leak up into the stack. For example, your web application needs to understand the underlying protocol when using the secure flag for cookies. If you don't get this right, your HTTP development server won't be able to read the cookies it writes, or worse, your HTTPS production server could pass sensitive cookies over an insecure connection.
Use production SSL certificates locally. This is annoying

	#!/usr/bin/env ruby
	# Usage: gitio URL [CODE]
	#
	# Turns a github.com URL
	# into a git.io URL
	#
	# Copies the git.io URL to your clipboard.

	url = ARGV[0]
	code = ARGV[1]

	// 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'];

	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

	# Nginx+Unicorn best-practices congifuration guide. Heartbleed fixed.
	# We use latest stable nginx with fresh openssl, zlib and pcre dependencies.
	# Some extra handy modules to use: --with-http_stub_status_module --with-http_gzip_static_module
	#
	# Deployment structure
	#
	# SERVER:
	# /etc/init.d/nginx (1. nginx)
	# /home/app/public_html/app_production/current (Capistrano directory)
	#

	<!DOCTYPE html>
	<html>
	<head>
	<meta charset=utf-8 />
	<title>Hello</title>
	<link rel="stylesheet" href="styles.css">
	</head>
	<body>
	Hello World
	</body>

	// Support routines for automatically reporting user timing for common analytics platforms
	// Currently supports Google Analytics, Boomerang and SOASTA mPulse
	// In the case of boomerang, you will need to map the event names you want reported
	// to timer names (for mPulse these need to be custom0, custom1, etc) using a global variable:
	// rumMapping = {'aft': 'custom0'};
	(function() {
	var wtt = function(n, t, b) {
	t = Math.round(t);
	if (t >= 0 && t < 3600000) {
	// Google Analytics