Thomas Jensen thomasjsn

F1. FS 128k streaming writes

Benchmark: fio write

Command: fio --name=seqwrite --rw=write --bs=128k --size=4g --end_fsync=1 --loops=4 # aggrb tput

Rationale: Measure the performance of a single threaded streaming write of a reasonably large file. The aim is to measure how well the file system and platform can sustain a write workload, which will depend on how well it can group and dispatch writes. It's difficult to benchmark buffered file system writes in both a short duration and in a repeatable way, as performance greatly depends on if and when the pagecache begins to flush dirty data. As a workaround, an fsync() at the end of the benchmark is called to ensure that flushing will always occur, and the benchmark also repeats four times. While this provides a much more reliable measurement, it is somewhat worst-case (applications don't always fsync), providing closer to a minimum rate – rather than a maximum rate – that you should expect.

F2. FS cached 4k random reads

Encoding Video

Installing

Install FFmpeg with homebrew. You'll need to install it with a couple flags for webm and the AAC audio codec.

brew install ffmpeg --with-libvpx --with-libvorbis --with-fdk-aac --with-opus

Parameters

Container: MP4

Parameter	YouTube recommends setting
-movflags faststart	moov atom at the front of the file (Fast Start)

Video codec: H.264

Guide to PROGMEM on ESP8266 and Arduino IDE

Intro

On low memory devices like the arduino and esp8266 you do not want strings to be stored in RAM. This occurs by default on these systems. Declare a string const char * xyz = "this is a string" and it will use up RAM.

The solution on these devices is to allow strings to be stored in read only memory, in Arduino this is the PROGMEM macro. Most of my experience is with the ESP8266 which is a 32bit micros controller. This device stores PROGMEM data in flash. The macro PROGMEM on ESP8266 is simply

#define PROGMEM   ICACHE_RODATA_ATTR

	console.log('Loading event');

	var Q = require('q');
	var aws = require('aws-sdk');
	var cloudfront = new aws.CloudFront();

	exports.handler = function (event, context) {
	//_log('Received event: ', event);

	var bucket = event.Records[0].s3.bucket.name;

	#!/bin/bash
	#

	BACKUPDEST="$1"
	DOMAIN="$2"
	MAXBACKUPS="$3"

	if [ -z "$BACKUPDEST" -o -z "$DOMAIN" ]; then
	echo "Usage: ./vm-backup <backup-folder> <domain> [max-backups]"
	exit 1

	global
	log 127.0.0.1 local0 debug
	chroot /var/lib/haproxy
	user haproxy
	group haproxy
	daemon
	tune.ssl.default-dh-param 2048

	defaults
	log global

	<?php

	namespace App\Events;

	use Illuminate\Contracts\Broadcasting\ShouldBroadcast;
	use Illuminate\Queue\SerializesModels;

	class NewMessage extends Event implements ShouldBroadcast
	{

	#!/bin/bash

	name=$RANDOM
	url='http://localhost:9093/api/v1/alerts'

	echo "firing up alert $name"

	# change url o
	curl -XPOST $url -d "[{
	\"status\": \"firing\",