jboner

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

samth

Emails from Matthew

http://lists.racket-lang.org/users/archive/2005-August/009483.html

http://lists.racket-lang.org/users/archive/2005-November/010350.html

http://lists.racket-lang.org/users/archive/2006-June/013819.html

http://lists.racket-lang.org/users/archive/2006-August/014439.html

massar

# Example nginx + git HTTP Smart mode (git-http-backend) + HTTP Authentication + HTTPS redirect
# jeroen@massar.ch - http://jeroen.massar.ch
 
server {
  listen  192.0.1.1:80;
  listen  [2001:db8::1]:80;
 
  # Redirect all non-HTTPS traffic to the HTTPS variant
  return 301 https://$host$request_uri;
}

archerslaw

# QEMU Monitor Protocol Python class
#
# Copyright (C) 2009 Red Hat Inc.
#
# This work is licensed under the terms of the GNU GPL, version 2.  See
# the COPYING file in the top-level directory.

import socket, json, time, commands
from optparse import OptionParser

isaacs

# Hello, and welcome to makefile basics.
#
# You will learn why `make` is so great, and why, despite its "weird" syntax,
# it is actually a highly expressive, efficient, and powerful way to build
# programs.
#
# Once you're done here, go to
# http://www.gnu.org/software/make/manual/make.html
# to learn SOOOO much more.

teh

{
    "acKind": "ImageManifest",
    "acVersion": "0.7.0",
    "name": "my-app",
    "labels": [
        {"name": "os", "value": "linux"},
        {"name": "arch", "value": "amd64"}
    ],
    "app": {
        "exec": [

edolstra

General notes

• nix-channel and ~/.nix-defexpr are gone. We'll use $NIX_PATH (or user environment specific overrides configured via nix set-path) to look up packages. Since $NIX_PATH supports URLs nowadays, this removes the need for channels: you can just set $NIX_PATH to e.g. https://nixos.org/channels/nixos-15.09/nixexprs.tar.xz and stay up to date automatically.

• By default, packages are selected by attribute name, rather than the name attribute. Thus nix install hello is basically equivalent to nix-env -iA hello. The attribute name is recorded in the user environment manifest and used in upgrades. Thus (at least by default) hello won't be upgraded to helloVariant.

  @vcunat suggested making this an arbitrary Nix expression rather than an attrpath, e.g. firefox.override { enableFoo = true; }. However, such an expression would not have a key in the user environment, unlike an attrpath. Better to require an explicit flag for this.

TBD: How to deal with search path clashes.

devimc

Hot plugging devices using ACPI, SHPC and native

This gist is to show different ways to hot plug devices in a Virtual Machine

Set up the environment

Create a device mapper

dd if=/dev/zero of=devmap.img count=1 bs=50M

Misairu-G

Reddit post (Archived)

Table of Content

• What to expect?
  • Some TLDR about the idea behind
• Prerequisites
  • Hardware
  • System & Software
• Update: Attention for MUXless laptop

edolstra

This document contains some ideas for additions to the Nix language.

Motivation

The Nix package manager, Nixpkgs and NixOS currently have several problems:

• Poor discoverability of package options. Package functions have function arguments like enableFoo, but there is no way for the Nix UI to discover them, let alone to provide programmatic ways to