Dave Henderson hairyhenderson

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

The new Docker daemon uses port: 2376 with TLS enable by default. Sometimes I want to play with curl on the old plain http port 2375. The trick is: use socat in a container to proxy the unix socket to a real port.

docker run -d \
  --volume /var/run/docker.sock:/var/run/docker.sock \
  --name docker-http \
  deb socat -d -d TCP-L:2375,fork UNIX:/var/run/docker.sock

Kubectl output options

Let's look at some basic kubectl output options.

Our intention is to list nodes (with their AWS InstanceId) and Pods (sorted by node).

We can start with:

kubectl get no

2021 Update: Easiest option is Justin's repo and image

Just run this from your Mac terminal and it'll drop you in a container with full permissions on the Docker VM. This also works for Docker for Windows for getting in Moby Linux VM (doesn't work for Windows Containers).

docker run -it --rm --privileged --pid=host justincormack/nsenter1

more info: https://github.com/justincormack/nsenter1

Java in Docker pitfalls

Why Java is a special case

JVM ergonomics
Libraries ergonomics

JVM and libraries decide how much memory and how many threads to use.

Client side searching for Hugo.io with Fuse.js

WHY
Sample
Setup
Files

layouts/_default/index.json

	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


	#include <IRremote.h>

	/*

	Send infrared commands from the Arduino to the iRobot Roomba
	by probono

	2013-03-17 Initial release

	<powershell>
	winrm quickconfig -q
	winrm set winrm/config/winrs '@{MaxMemoryPerShellMB="300"}'
	winrm set winrm/config '@{MaxTimeoutms="1800000"}'
	winrm set winrm/config/service '@{AllowUnencrypted="true"}'
	winrm set winrm/config/service/auth '@{Basic="true"}'

	netsh advfirewall firewall add rule name="WinRM 5985" protocol=TCP dir=in localport=5985 action=allow
	netsh advfirewall firewall add rule name="WinRM 5986" protocol=TCP dir=in localport=5986 action=allow

	/*
	Firmata is a generic protocol for communicating with microcontrollers
	from software on a host computer. It is intended to work with
	any host computer software package.

	To download a host software package, please clink on the following link
	to open the list of Firmata client libraries your default browser.

	https://github.com/firmata/arduino#firmata-client-libraries