bitonic

// See companion blog post <https://mazzo.li/posts/crc-tips.html> for
// extended commentary.
//
// Compiled with
//
//   % clang++ --version                                                                         
//   clang version 17.0.6
//   % clang++ -std=c++20 -march=raptorlake -Wall crc32c-tips.cpp -o crc32c-tips
#include <stdint.h>
#include <stdio.h>

bitonic

// See <https://mazzo.li/posts/stopping-linux-threads.html>
// for blog post.
//
// Spawns a thread with a server listening on 55555 UDP, and
// then terminates it after 1 minute.
//
// I compile and run with
//
//     clang++ -Wall -std=c++20 server.cpp -lpthread -o server && ./server
//

bitonic

# From <https://github.com/clefru/nur-packages/tree/f633986f5e31afdd130595b6dc0dea6824d69ef9/pkgs/ib-tws>
{ pkgs ? import <nixpkgs> {} }:
with pkgs;

let
twsWrap = builtins.toFile "tws-wrap.sh" ''
  #!/bin/sh
  export INSTALL4J_JAVA_HOME_OVERRIDE='__JAVAHOME__'
  mkdir -p $HOME/.tws
  VMOPTIONS=$HOME/.tws/tws.vmoptions

bitonic

# If TEST_RACE = False, no exception is thrown. If it's True, it is. The only difference is
# a sleep in _joinrealpath.
TEST_RACE = False

import os
import time
import threading
import pathlib

def realpath(filename):

bitonic

/*
Benchmark for Eigen change, see <https://gitlab.com/libeigen/eigen/-/merge_requests/734#note_743674873>

Comment reported here for posterity:

Here's a synthetic "benchmark" which I _believe_ shows the difference: https://gist.github.com/bitonic/2d09df858ba2233b7f472f5f8c0512b4 .

I say that I believe that it exhibits the difference because it shows the runtime differences that I'd expect, with some caveats (see comments on number of instructions below).

However, I have not inspected the assembly manually to check that the code varies in the way I'd expect, which would be a requirement to ensure that things change in the way we expect. That is a bit more labor intensive, and while I might do it, I don't have time to do it right now.

bitonic

# Full NixOS configuration for a ZFS server with full disk encryption hosted on Hetzner.
# See <https://mazzo.li/posts/hetzner-zfs.html> for more information.

{ config, pkgs, ... }:
let
  # Deployment-specific parameters -- you need to fill these in where the ... are

  hostName = "...";
  publicKey = "...";
  # From `ls -lh /dev/disk/by-id`

bitonic

{ lib
, stdenv
, coreutils
, callPackage
, makeWrapper
, requireFile
, python3
, writeTextFile
, binutils
, patchelf

bitonic

// Copyright (c) 2021 Francesco Mazzoli <[email protected]>
//
// Permission to use, copy, modify, and distribute this software for any
// purpose with or without fee is hereby granted, provided that the above
// copyright notice and this permission notice appear in all copies.
//
// THE SOFTWARE IS PROVIDED "AS IS" AND THE AUTHOR DISCLAIMS ALL WARRANTIES
// WITH REGARD TO THIS SOFTWARE INCLUDING ALL IMPLIED WARRANTIES OF
// MERCHANTABILITY AND FITNESS. IN NO EVENT SHALL THE AUTHOR BE LIABLE FOR
// ANY SPECIAL, DIRECT, INDIRECT, OR CONSEQUENTIAL DAMAGES OR ANY DAMAGES

bitonic

// See <https://gist.github.com/pervognsen/b58108d134824e61caedffcc01004e03> for
// Per Vognsen gist on value speculation.
//
// I compile this on linux with
//
//     $ clang --version
//     clang version 12.0.0
//     Target: x86_64-unknown-linux-gnu
//     $ clang -static -Wall -O3 value-speculation-linux.c -o value-speculation-linux
//

bitonic

{-# LANGUAGE MultiWayIf #-}
{-# LANGUAGE LambdaCase #-}
{-# LANGUAGE RecordWildCards #-}
import Data.List (transpose)

data Forward a = Forward { _value :: !a, _grad :: !a }
  deriving (Show, Eq)

lift :: Num a => a -> Forward a
lift a = Forward { _value = a, _grad = 0 }