javiermon

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

javiermon

Copyright 2018 Dominik Liebler

Permission is hereby granted, free of charge, to any person obtaining a copy of this software and associated documentation files (the "Software"), to deal in the Software without restriction, including without limitation the rights to use, copy, modify, merge, publish, distribute, sublicense, and/or sell copies of the Software, and to permit persons to whom the Software is furnished to do so, subject to the following conditions:

The above copyright notice and this permission notice shall be included in all copies or substantial portions of the Software.

THE SOFTWARE IS PROVIDED "AS IS", WITHOUT WARRANTY OF ANY KIND, EXPRESS OR IMPLIED, INCLUDING BUT NOT LIMITED TO THE WARRANTIES OF MERCHANTABILITY, FITNESS FOR A PARTICULAR PURPOSE AND NONINFRINGEMENT. IN NO EVENT SHALL THE AUTHORS OR COPYRIGHT HOLDERS BE LIABLE FOR ANY CLAIM, DAMAGES OR OTHER LIABILITY, WHETHER IN AN ACTION OF CONTRACT, TORT OR OTHERWISE, ARISING FROM, OUT OF OR IN CONNECTION WITH THE SOFTWARE OR THE USE OR O

javiermon

If you want to clone an svn repository with git-svn but don't want it to push all the existing branches, here's what you should do.

* Clone with git-svn using the -T parameter to define your trunk path inside the svnrepo, at the same time instructing it to clone only the trunk:
  
  git svn clone -T trunk http://example.com/PROJECT

* If instead of cloning trunk you just want to clone a certain branch, do the same thing but change the path given to -T:

  git svn clone -T branches/somefeature http://example.com/PROJECT

javiermon

#!/bin/bash
cat .gitignore | sed 's/^/\.\//g;s/\(.*\)\/\([0-9a-zA-Z\*\?\.]*\)$/svn propedit svn:ignore "\2" \1 /mg' | bash

javiermon

#! /usr/bin/env python

# Standard library imports.
from SocketServer import ThreadingMixIn
import BaseHTTPServer
import SimpleHTTPServer
import sys
import json
import os
from os.path import (join, exists, dirname, abspath, isabs, sep, walk, splitext,

javiermon

/* 
   iflist.c : retrieve network interface information thru netlink sockets

   (c) Jean Lorchat @ Internet Initiative Japan - Innovation Institute

   v1.0 : initial version - Feb 19th 2010

   This file was obtained at the following address :
   http://www.iijlab.net/~jean/iflist.c

javiermon

#!/usr/bin/env python

"""Simple HTTP Server With Upload.

This module builds on BaseHTTPServer by implementing the standard GET
and HEAD requests in a fairly straightforward manner.

"""

javiermon

High-level

I want to write about why GDB is a great tool for learning C. At least part of the difficulty in learning C is that the language isn’t as interactive as using Python or Ruby.

TL;DR You can kinda use gdb as a repl for c

What’s the smallest possible program we could debug to learn about pointers?

javiermon

#include <stdio.h>
#include <sys/socket.h>
#include <linux/netlink.h>
#include <linux/connector.h>
#include <linux/cn_proc.h>
#include <stdlib.h>
#include <errno.h>

struct __attribute__ ((aligned(NLMSG_ALIGNTO))) nlcn_msg {
  struct nlmsghdr nl_hdr;

javiermon

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname