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@mcastelino
mcastelino / qemu-tracing.md
Last active February 19, 2025 16:45
Tracing QEMU-KVM Interactions

Tracing QEMU-KVM Interactions

But default in linux you can figure out how many times and for what reasons there is a VM Exit from a VM into the kvm kernel module. However given the ubiquity of vhost and the ability of kvm to emulate most device models directly in the kernel, most of those VM exits do not result in a transition from host kernel into the QEMU. The transitions from VM -> kvm -> QEMU are typically the most expensive.

Here we try to figure out how many of the VM Exits result in the invocation of QEMU.

Tracking VM-KVM Interactions

This can be done very simply with perf

@AgentOak
AgentOak / youtube_formats.md
Last active June 10, 2026 08:21
Youtube Format IDs

Last updated: April 2021

Also known as itag or format codes and way back they could be specified with the fmt parameter (e.g. &fmt=22). Depending on the age and/or popularity of the video, not all formats will be available.

DASH video

Resolution AV1 HFR High AV1 HFR AV1 VP9.2 HDR HFR VP9 HFR VP9 H.264 HFR H.264
MP4 MP4 MP4 WebM WebM WebM MP4 MP4
Can't Copy/Paste in Google Docs on Firefox:
Set dom.event.clipboardevents.enabled on about:config to true
Speed-up Firefox's awesome bar / location bar:
browser.urlbar.delay to 0 speeds up the search response
layout.frame_rate 60
In "about:config" change "layout.frame_rate" from -1 to 60 (or whatever your monitor runs at).
For some stupid reason, Firefox renders as fast as your CPU can handle 100% of the time.
Even at 60 FPS, it uses ~1% CPU when idle so I'm guessing it was going like 6000FPS when unrestrained.
@drmalex07
drmalex07 / getopt-example.sh
Last active May 3, 2025 11:08
A small example on Bash getopts. #bash #getopt #getopts
#!/bin/bash
#
# Example using getopt (vs builtin getopts) that can also handle long options.
# Another clean example can be found at:
# http://www.bahmanm.com/blogs/command-line-options-how-to-parse-in-bash-using-getopt
#
aflag=n
bflag=n
@mattiaslundberg
mattiaslundberg / arch-linux-install
Last active June 8, 2026 14:22
Minimal instructions for installing arch linux on an UEFI system with full system encryption using dm-crypt and luks
# Install ARCH Linux with encrypted file-system and UEFI
# The official installation guide (https://wiki.archlinux.org/index.php/Installation_Guide) contains a more verbose description.
# Download the archiso image from https://www.archlinux.org/
# Copy to a usb-drive
dd if=archlinux.img of=/dev/sdX bs=16M && sync # on linux
# Boot from the usb. If the usb fails to boot, make sure that secure boot is disabled in the BIOS configuration.
# Set swedish keymap