borislav nikolov jackdoe

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

Clojure Destructuring Tutorial and Cheat Sheet

(Related blog post)

Simply put, destructuring in Clojure is a way extract values from a datastructure and bind them to symbols, without having to explicitly traverse the datstructure. It allows for elegant and concise Clojure code.

	obj-m += tcp_svr_sample.o

	all:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) modules

	clean:
	make -C /lib/modules/$(shell uname -r)/build M=$(PWD) clea

	# In a MongoMapper::Document,
	# simply add
	# key :password, Password
	# your password will be automatically hashed,
	# and you can compare plain-text passwords with the user's hashed password, ruby style:
	# User.first.password == '1234'
	# => true
	#
	# Also, prevents passwords from being leaked onto the console or error messages:
	# User.first.password

	Dear soon-to-be-former user,

	We've got some fantastic news! Well, it's great news for us anyway. You, on
	the other hand, are fucked.

	We've just been acquired by:

	[ ] Facebook
	[ ] Google
	[ ] Twitter

	#!/usr/bin/env sh

	##
	# This is script with usefull tips taken from:
	# https://github.com/mathiasbynens/dotfiles/blob/master/.osx
	#
	# install it:
	# curl -sL https://raw.github.com/gist/2108403/hack.sh \| sh
	#

	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

	// Just before switching jobs:
	// Add one of these.
	// Preferably into the same commit where you do a large merge.
	//
	// This started as a tweet with a joke of "C++ pro-tip: #define private public",
	// and then it quickly escalated into more and more evil suggestions.
	// I've tried to capture interesting suggestions here.
	//
	// Contributors: @r2d2rigo, @joeldevahl, @msinilo, @_Humus_,
	// @YuriyODonnell, @rygorous, @cmuratori, @mike_acton, @grumpygiant,

	[
	{ "name": "Shanghai", "lat": 31.22222, "lng": 121.45806 },
	{ "name": "Buenos Aires", "lat": -34.61315, "lng": -58.37723 },
	{ "name": "Mumbai", "lat": 19.07283, "lng": 72.88261 },
	{ "name": "Mexico City", "lat": 19.42847, "lng": -99.12766 },
	{ "name": "Beijing", "lat": 39.9075, "lng": 116.39723 },
	{ "name": "Karachi", "lat": 24.9056, "lng": 67.0822 },
	{ "name": "Istanbul", "lat": 41.01384, "lng": 28.94966 },
	{ "name": "Tianjin", "lat": 39.14222, "lng": 117.17667 },
	{ "name": "Guangzhou", "lat": 23.11667, "lng": 113.25 },

	"""
	Minimal character-level Vanilla RNN model. Written by Andrej Karpathy (@karpathy)
	BSD License
	"""
	import numpy as np

	# data I/O
	data = open('input.txt', 'r').read() # should be simple plain text file
	chars = list(set(data))
	data_size, vocab_size = len(data), len(chars)

borislav nikolov jackdoe

Latency numbers every programmer should know

Clojure Destructuring Tutorial and Cheat Sheet

Vectors and Sequences