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KVM - vhost-net vs Userspace Host CPU Performance Comparison

I've been kicking the tires recently on a new KVM server I'm using for a home lab, and one of the things I've been investigating recently is network optimization in the guest.

Being especially anal about it and during my investigation of whether or not I could reasonably fix an approximately 500usec latency difference between pinging the guest and host, I started to look into making sure vhost-net was enabled on my rudimentary and extremely minimal KVM host running Alpine Linux. After ultimately getting it set up and finding the same latency, I wanted to see where the real value laid with having this setup on what will ultimately still be a not-so-busy low-end machine. I found some interesting results!

TL;DR: at the very least, vhost-net will save you a decent amount of CPU. Read on!

The test setup

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#!/usr/bin/env sh

spctl -a -vv "$1" && codesign --test-requirement="=notarized" --verify --verbose "$1" && codesign -dv --verbose=4 "$1"

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layout node

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alias tolower='tr '\''[:upper:]'\'' '\''[:lower:]'\'''

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Installing old Versions of Packages With Homebrew

https://cmichel.io/how-to-install-an-old-package-version-with-brew/

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#!/bin/sh

lsof -Pni

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#!/usr/bin/env sh

spctl -a -vv "$1" && codesign --test-requirement="=notarized" --verify --verbose "$1" && codesign -dv --verbose=4 "$1"

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Run SSH Agent w/Modified Options (MacOS Big Sur, No Homebrew, No SIP Modification)

The following will show you how you can modify the startup options of the SSH agent supplied by MacOS in a non-invasive way. This can be useful for doing things like setting a key lifetime, which can then be used with AddKeysToAgent in your ~/.ssh/config to automate the timing out of saved keys. This ensures that your passphrase is re-asked for periodically without having to shutdown, re-log, or having it actually persisted in keychain, the latter being almost as bad as having no passphrase at all, given that simply being logged in is generally enough to then use the key.

This method does not modify the system-installed SSH agent service (com.openssh.ssh-agent), but rather duplicates its functionality into a user-installed launch agent where we can then modify the options. Modifying the system-installed service is becoming increasingly harder to do; SIP generally protects

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#!/usr/bin/env bash

getproviders() {
  for (( PAGE=1; ; PAGE++ )); do
    if [ "$1" == "--community" ]; then
      DATA="$(curl -fs "https://registry.terraform.io/v2/providers?filter[tier]=community&page[number]=$PAGE")"
    else
      DATA="$(curl -fs "https://registry.terraform.io/v2/providers?page[number]=$PAGE")"
    fi

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package main

import "fmt"

const fooBar = `
resource "foo" "bar" {
  a = "b"
}
`