Owen Kelly ojkelly

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

External Resources

linuxacademy.com (Training)
Acloud.guru (training)
Read the top-level Documentation and FAQs for all the major AWS resources (EC2, S3, RDS, Auto Scaling, etc). The answers to the "nit-picky" questions can be found here. It's also helpful to go deeper on VPCs and networking-related concepts.
- VPC http://docs.aws.amazon.com/AWSEC2/latest/UserGuide/using-vpc.html
- VPC Security http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Security.html
- VPC Route Tables http://docs.aws.amazon.com/AmazonVPC/latest/UserGuide/VPC_Route_Tables.html
Everyone says read the white papers. The ones I read were:
- Security Best Practices https://d0.awsstatic.com/whitepapers/Security/AWS_Security_Best_Practices.pdf
Cloud Best Practices https://d0.awsstatic.com/whitepapers/AWS_Cloud_Best_Practices.pdf

Algebraic Effects in JavaScript part 1 - continuations and control transfer

This is the first post of a series about Algebraic Effects and Handlers.

There are 2 ways to approach this topic:

Denotational: explain Algebraic Effects in terms of their meaning in mathematics/Category theory
Operational: explain the mechanic of Algebraic Effects by showing how they operate under a chosen runtime environment

Both approaches are valuables and give different insights on the topic. However, not everyone (including me), has the prerequisites to grasp the concepts of Category theory and Abstract Algebra. On the other hand, the operational approach is accessible to a much wider audience of programmers even if it doesn't provide the full picture.

Computational Fluid Dynamics (in graphics mostly)

Disclaimer: I have no professional education in Compulational Fluid Dynamics, these are various notes on what I found/learned when trying to learn a bit on the topic. Some of the notes lack sources as I wrote them up later often just remembering some StackExchange answer. Some things I might have misinterpreted.

Computational Fluid Dynamics (in graphics mostly)
General / Overview
- Overarching resources
General Concepts & Keywords

	# ~/.gitconfig from @boblet
	# initially based on http://rails.wincent.com/wiki/Git_quickstart

	[core]
	excludesfile = /Users/oli/.gitignore
	legacyheaders = false # >git 1.5
	quotepath = false
	# http://stackoverflow.com/questions/136178/git-diff-handling-long-lines
	pager = less -r
	# if ↑ doesn’t work, try: pager = less -+$LESS -FRX

	sudo defaults write /Library/Preferences/com.apple.windowserver DisplayResolutionEnabled -bool YES;
	sudo defaults delete /Library/Preferences/com.apple.windowserver DisplayResolutionDisabled;

	// by the way, you need to logout and log back in for this to take effect. Or at least that's what
	// Quartz Debug says. Who knows, maybe it's lying?

	// P.S. Go to [Apple menu --> System Preferences --> Displays --> Display --> Scaled] after logging
	// back in, and you'll see a bunch of "HiDPI" resolutions in the list to choose from.

	* {
	font-size: 12pt;
	font-family: monospace;
	font-weight: normal;
	font-style: normal;
	text-decoration: none;
	color: black;
	cursor: default;
	}

	#!/bin/bash

	# Bash script for setting or clearing touch requirements for
	# cryptographic operations the OpenPGP application on a YubiKey 4.
	#
	# Author: Alessio Di Mauro <[email protected]>

	GCA=$(which gpg-connect-agent)
	DO=0
	UIF=0