Thujeevan thujeevan

High-Performance Matrix Multiplication

This is a short post that explains how to write a high-performance matrix multiplication program on modern processors. In this tutorial I will use a single core of the Skylake-client CPU with AVX2, but the principles in this post also apply to other processors with different instruction sets (such as AVX512).

Intro

Matrix multiplication is a mathematical operation that defines the product of

Note:

When this guide is more complete, the plan is to move it into Prepack documentation.
For now I put it out as a gist to gather initial feedback.

A Gentle Introduction to Prepack (Part 1)

If you're building JavaScript apps, you might already be familiar with some tools that compile JavaScript code to equivalent JavaScript code:

Babel lets you use newer JavaScript language features, and outputs equivalent code that targets older JavaScript engines.

Adjusting child processes for PHP-FPM (Nginx)

When setting these options consider the following:

How long is your average request?
What is the maximum number of simultaneous visitors the site(s) get?
How much memory on average does each child process consume?

Determine if the max_children limit has been reached.

sudo grep max_children /var/log/php?.?-fpm.log.1 /var/log/php?.?-fpm.log

Migrations & Seeding

What are migrations??

Migrations are a way to make database changes or updates, like creating or dropping tables, as well as updating a table with new columns with constraints via generated scripts. We can build these scripts via the command line using knex command line tool.

To learn more about migrations, check out this article on the different types of database migrations!

Creating/Dropping Tables

Distilling the Essence of Reducers

Redux has brought the notion of reducer back into the awareness of many developers for whom they are a novel concept. In fact they are quite simple, and used all the time in such things as SUM aggregations in databases, where they compute a single value from many.

It's great that Redux has made reducers known to a broader audience, though they are relatively ancient concepts in programming, in fact. But the particular way Redux illustrates a reducer in its documentaion is, in my opinion, with a coding style that is harder to extend and read than it should be. Let's distill reducers down to their essensce, and build up Redux reducers in a way that lowers complexity, and helps separate Redux idioms from your business logic.

The simplest reducer

A reducer is a pure function that accepts more arguments than it returns. That is to say - one whose "arity" is greater than 1. It 'reduces' the two things you pass it down to a single value. Here are two reducers, in a map

Don't use VPN services.

No, seriously, don't. You're probably reading this because you've asked what VPN service to use, and this is the answer.

Note: The content in this post does not apply to using VPN for their intended purpose; that is, as a virtual private (internal) network. It only applies to using it as a glorified proxy, which is what every third-party "VPN provider" does.

A Russian translation of this article can be found here, contributed by Timur Demin.
A Turkish translation can be found here, contributed by agyild.
There's also this article about VPN services, which is honestly better written (and has more cat pictures!) than my article.

	.unreset {
	a {
	@apply text-blue-700 underline;
	}
	p {
	@apply my-4;
	}

	blockquote,
	figure {

	#!/bin/bash

	# Give the usual warning.
	clear;
	echo "[INFO] Automated Android root script started.\n\n[WARN] Exploit requires sdk module \"NDK\".\nFor more information, visit the installation guide @ https://goo.gl/E2nmLF\n[INFO] Press Ctrl+C to stop the script if you need to install the NDK module. Waiting 10 seconds...";
	sleep 10;
	clear;

	# Download and extract exploit files.
	echo "[INFO] Downloading exploit files from GitHub...";

	/**
	* Using Operator Mono in Atom
	*
	* 1. Open up Atom Preferences.
	* 2. Click the “Open Config Folder” button.
	* 3. In the new window’s tree view on the left you should see a file called “styles.less”. Open that up.
	* 4. Copy and paste the CSS below into that file. As long as you have Operator Mono SSm installed you should be golden!
	* 5. Tweak away.
	*
	* Theme from the screenshot (http://cdn.typography.com/assets/images/blog/operator_ide2.png):