kconner

macOS Internals

Understand your Mac and iPhone more deeply by tracing the evolution of Mac OS X from prelease to Swift. John Siracusa delivers the details.

Starting Points

How to use this gist

You've got two main options:

pervognsen

# Hash, displace, and compress: http://cmph.sourceforge.net/papers/esa09.pdf
# This is expected linear time for any seeded hash function that acts like a random hash function (universality isn't enough).
# (Actually, the code as written is O(n log n) when targeting 100% load. It's O(n) when targeting any smaller load factor.)
# You can make keys_per_bucket higher than the default of 4 but construction time will start to increase dramatically.
# The paper this is based on compresses the seeds (so the fact that the algorithm tries seeds in increasing order is important)
# which brings the representation size close to the information-theoretical minimum. I don't do any of that here, but it could
# be done as a postprocess.
def make_perfect_hash(keys, load_factor=1.0, keys_per_bucket=4, rhash=murmurhash, max_seed=1000000):
    m = int(len(keys) / load_factor)
    r = int(len(keys) / keys_per_bucket)

skeeto

Moved to skeeto/scratch/aidrivers

ddevault

WAYLAND_PROTOCOLS=/usr/share/wayland-protocols

# wayland-scanner is a tool which generates C headers and rigging for Wayland
# protocols, which are specified in XML. wlroots requires you to rig these up
# to your build system yourself and provide them in the include path.
xdg-shell-protocol.h:
	wayland-scanner server-header \
		$(WAYLAND_PROTOCOLS)/stable/xdg-shell/xdg-shell.xml $@

xdg-shell-protocol.c: xdg-shell-protocol.h

quantumjim

# coding: utf-8

from creative import *

def clear_screen():

    for _ in range(50):
        print("")

def get_percentage(stats,string):

nadavrot

High-Performance Matrix Multiplication

This is a short post that explains how to write a high-performance matrix multiplication program on modern processors. In this tutorial I will use a single core of the Skylake-client CPU with AVX2, but the principles in this post also apply to other processors with different instruction sets (such as AVX512).

Intro

Matrix multiplication is a mathematical operation that defines the product of

enricofoltran

package main

import (
	"context"
	"flag"
	"fmt"
	"log"
	"net/http"
	"os"
	"os/signal"

djspiewak

Quick Tips for Fast Code on the JVM

I was talking to a coworker recently about general techniques that almost always form the core of any effort to write very fast, down-to-the-metal hot path code on the JVM, and they pointed out that there really isn't a particularly good place to go for this information. It occurred to me that, really, I had more or less picked up all of it by word of mouth and experience, and there just aren't any good reference sources on the topic. So… here's my word of mouth.

This is by no means a comprehensive gist. It's also important to understand that the techniques that I outline in here are not 100% absolute either. Performance on the JVM is an incredibly complicated subject, and while there are rules that almost always hold true, the "almost" remains very salient. Also, for many or even most applications, there will be other techniques that I'm not mentioning which will have a greater impact. JMH, Java Flight Recorder, and a good profiler are your very best friend! Mea

aparrish

kennwhite

package main

import (
	"crypto/tls"
	"golang.org/x/crypto/acme/autocert"
	"log"
	"net"
	"net/http"
)