jboner

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

hellerbarde

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

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

rondy

FWIW: I (@rondy) am not the creator of the content shared here, which is an excerpt from Edmond Lau's book. I simply copied and pasted it from another location and saved it as a personal note, before it gained popularity on news.ycombinator.com. Unfortunately, I cannot recall the exact origin of the original source, nor was I able to find the author's name, so I am can't provide the appropriate credits.

---

Effective Engineer - Notes

• By Edmond Lau
• Highly Recommended 👍
• http://www.theeffectiveengineer.com/

What's an Effective Engineer?

branneman

Better local require() paths for Node.js

Problem

When the directory structure of your Node.js application (not library!) has some depth, you end up with a lot of annoying relative paths in your require calls like:

const Article = require('../../../../app/models/article');

Those suck for maintenance and they're ugly.

Possible solutions

yossorion

What I Wish I'd Known About Equity Before Joining A Unicorn

Disclaimer: This piece is written anonymously. The names of a few particular companies are mentioned, but as common examples only.

This is a short write-up on things that I wish I'd known and considered before joining a private company (aka startup, aka unicorn in some cases). I'm not trying to make the case that you should never join a private company, but the power imbalance between founder and employee is extreme, and that potential candidates would

simme

# First install tmux
brew install tmux

# For mouse support (for switching panes and windows)
# Only needed if you are using Terminal.app (iTerm has mouse support)
Install http://www.culater.net/software/SIMBL/SIMBL.php
Then install https://bitheap.org/mouseterm/

# More on mouse support http://floriancrouzat.net/2010/07/run-tmux-with-mouse-support-in-mac-os-x-terminal-app/

eloylp

Fedora35 hibernation

This guide helps to configure the hibernation on a default Fedora35 (also worked fine in previous Fedora34) installation by using a swap file. The Fedora35 installation comes with btrfs as default filesystem. Also, it comes with a zram swap device:

$ swapon
NAME       TYPE      SIZE USED PRIO
/dev/zram0 partition   8G   0B  100

ck-on

<?php
/*
OCP - Opcache Control Panel   (aka Zend Optimizer+ Control Panel for PHP)
Author: _ck_   (with contributions by GK, stasilok)
Version: 0.1.7
Free for any kind of use or modification, I am not responsible for anything, please share your improvements

* revision history
0.1.7  2015-09-01  regex fix for PHP7 phpinfo
0.1.6  2013-04-12  moved meta to footer so graphs can be higher and reduce clutter

UMU18

<?php
//answer for https://www.testdome.com/questions/php/file-owners/11840?visibility=17&skillId=5
class FileOwners
{
    public static function groupByOwners($files)
    {
        $result=array();
        foreach($files as $key=>$value)
        {
            $result[$value][]=$key;