j-keck

Problem

The MPOW Bluetooth 5 dongle (Model: BH456A) does not work out of the box on Ubuntu 20.04 (kernel 5.4.0-42).

Solution

Patch the bluetooth kernel module and copy the firmware binaries to /lib/firmware.

Copy the fimware

j-keck

# NVM
curl -o- https://raw.githubusercontent.com/creationix/nvm/v0.33.11/install.sh | bash
export NVM_DIR="$HOME/.nvm"
[ -s "$NVM_DIR/nvm.sh" ] && \. "$NVM_DIR/nvm.sh"  # This loads nvm
[ -s "$NVM_DIR/bash_completion" ] && \. "$NVM_DIR/bash_completion"  # This loads nvm bash_completion
nvm install 10

# Yarn
curl -o- -L https://yarnpkg.com/install.sh | bash
export PATH="$HOME/.yarn/bin:$HOME/.config/yarn/global/node_modules/.bin:$PATH"

j-keck

{
  "Version": "2012-10-17",
  "Id": "arn:aws:sqs:YOUR-AWS-REGION:YOUR-AWS-ACCOUNT-ID:YOUR-QUEUE-NAME/SQSDefaultPolicy",
  "Statement": [
    {
      "Sid": "example-statement-ID",
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },

j-keck

{
  "Version": "2012-10-17",
  "Id": "arn:aws:sqs:YOUR-AWS-REGION:YOUR-AWS-ACCOUNT-ID:YOUR-QUEUE-NAME/SQSDefaultPolicy",
  "Statement": [
    {
      "Sid": "example-statement-ID",
      "Effect": "Allow",
      "Principal": {
        "AWS": "*"
      },

j-keck

kubectl api-resources --verbs=list --namespaced -o name  | while read name; do  echo -e "\n$name:"; kubectl get -A --show-kind $name;done 

j-keck

//
// covid19 dataset from https://pavelmayer.de/covid/risks/
// 
//   amm script.sc fetch        : fetch the actual day
//   amm script.sc cron         : fetch every 24 hours
//   amm script.sc show <region>: show the last dataset for <region> (default: Ortenaukreis)
//   amm script.sc list <region>: list all datasets for <region> (default: Ortenaukreis)
//
import $ivy.`org.http4s::http4s-blaze-client:0.21.4`
import $ivy.`co.fs2::fs2-core:2.2.1`

j-keck

import sbt._
import sbt.Keys._

import sbtassembly.AssemblyPlugin, AssemblyPlugin.autoImport._

object ProguardKeys {
  val proguard = taskKey[File]("builds the proguarded jar file")
  val proguardOptions = settingKey[Seq[String]]("CLI options")
  val proguardVersion = settingKey[String]("proguard's artefact version")

j-keck

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

j-keck

#!/usr/bin/env stap

#
# logs sync events triggered from postgres
#
#
# example output:
#
#  = table insert =
#

j-keck

create a vm

root@main:~ # vm create -t debian -s 100G nixos
root@main:~ # vm iso /stuff/downloads/nixos-graphical-18.03.132192.ce0d9d638de-x86_64-linux.iso 
root@main:~ # vm -f install nixos nixos-graphical-18.03.132192.ce0d9d638de-x86_64-linux.iso

boot the image

determine the 'init' executable path from '(cd0)/isolinux/isolinux.cfg'. look for a line which start's with: 'APPEND init=/nix/store/.....'