Yeongpil Y. ziwon

GNU Make Cheatsheet

Based on https://www.gnu.org/software/make/manual/html_node/Quick-Reference.html

Directives

Directive	Description
`define variable` `define variable =` `define variable :=` `define variable ::=` `define variable +=` `define variable ?=` `endef`	Define multi-line variables.
`undefine variable`	Undefining variables.

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

Lima (Linux virtual machines, on macOS) installation guide for M1 Mac.

Sep. 27th 2021 UPDATED

Now we can install patched version of QEMU via Homebrew (thank you everyone for the info!). Here is the updated instruction with it:

Used M1 Mac mini 2020 with macOS Big Sur Version 11.6.

1. Install QEMU & Lima

Kafka-node consumer benchmark

This code can be used to benchmark throughput for a kafka cluster. Args:

groupId -- (str) kafka consumer group id, default: bench
concurrency -- (int) Number of worker threads to spawn, defaults to number of cpus on current host
duration -- (int) How long to run the benchmark for, default: 20s
topic -- (str) the kafka topic to consume from, defaults to observations.json
zk -- (str) zookeeper url, defaults to localhost:2181

AWS Route 53 white label nameserver setup

Also see: AWS CLI Setup

	#!/usr/bin/env bash
	####################################################################################
	# Slack Bash console script for sending messages.
	####################################################################################
	# Installation
	# $ curl -s https://gist.githubusercontent.com/andkirby/67a774513215d7ba06384186dd441d9e/raw --output /usr/bin/slack
	# $ chmod +x /usr/bin/slack
	####################################################################################
	# USAGE
	# Send message to slack channel/user

	#!/bin/bash
	# Requires: awscli (http://aws.amazon.com/cli/)
	# Prints out a list of all security groups and their settings, just for quickly auditing it.

	# Your AWS credentials
	if [ -z ${AWS_ACCESS_KEY_ID} ]; then
	export AWS_ACCESS_KEY_ID='***'
	export AWS_SECRET_ACCESS_KEY='***'
	fi

	#!/bin/bash
	PATH=/usr/local/sbin:/usr/local/bin:/usr/sbin:/usr/bin:/sbin:/bin:/snap/bin:/snap/bin
	log="/var/log/aws_inspector/aws_inspector_export_rep.log"
	template_arn='arn:aws:inspector:us-east-1:XXXXXXXXXXXX:target/xxxxxxxxxx/template/xxxxxxxxxx'
	wait_sec='5400'

	log_out(){
	(($verifymon)) &&\
	echo -e "`date +'%Y-%m-%d %H:%M:%S'` (pid $$) -- $1" >> $log \|\|\
	echo -e "`date +'%Y-%m-%d %H:%M:%S'` (pid $$) -- $1" \| tee -a $log

	#XLarge DBInstanceClassMemory = 15892177440 = 14.8GB
	#/32 = 496630545 = 473MB
	#/64 = 248315272 = 236MB
	#/128 = 124157636 = 118MB
	#/256 = 62078818 = 59MB
	#/512 = 31039409 = 29MB
	#/12582880 = 1263 #default same divisor as max_connections = 4041.6MB = 4237924762
	#/25165760 = 623 # half of max_connections = 1993.6MB
	#/50331520 = 315 # quarter of max_connections = 1008MB = 1056964608
	#*(3/4) #default innodb pool size = 11922309120

	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