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

hellerbarde

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns
L2 cache reference ........................... 7 ns
Mutex lock/unlock ........................... 25 ns
Main memory reference ...................... 100 ns             
Compress 1K bytes with Zippy ............. 3,000 ns  =   3 µs
Send 2K bytes over 1 Gbps network ....... 20,000 ns  =  20 µs
SSD random read ........................ 150,000 ns  = 150 µs

Read 1 MB sequentially from memory ..... 250,000 ns = 250 µs

zchothia

// AVX CPU dispatching - based on Agner Fog's C++ vector class library:
// http://www.agner.org/optimize/vectorclass.zip

#include <stdio.h>
#include <stdbool.h>

//------------------------------------------------------------------------------
//>> BEGIN <instrset.h>

// Detect 64 bit mode

cobyism

Deploying a subfolder to GitHub Pages

Sometimes you want to have a subdirectory on the master branch be the root directory of a repository’s gh-pages branch. This is useful for things like sites developed with Yeoman, or if you have a Jekyll site contained in the master branch alongside the rest of your code.

For the sake of this example, let’s pretend the subfolder containing your site is named dist.

Step 1

Remove the dist directory from the project’s .gitignore file (it’s ignored by default by Yeoman).

pezz

Intro

Just some FYI, to get started:

• I'm using a 16 GB Sandisk SD card.
• I have a model B Pi, 512 MB RAM (not really relevant, thought I'd mention it).
• Monitor and keyboard connected to the Pi itself, for now.
• Network working, internet access.

willurd

Each of these commands will run an ad hoc http static server in your current (or specified) directory, available at http://localhost:8000. Use this power wisely.

Discussion on reddit.

Python 2.x

$ python -m SimpleHTTPServer 8000

framon

# first you need a new empty branch; let's call it `newroot`
git checkout --orphan newroot
git rm -rf .

# then you apply the same steps
git commit --allow-empty -m 'root commit'
git rebase --onto newroot --root master
git branch -d newroot

jefferyto

# based on
# https://dev.openwrt.org/browser/trunk/target/linux/atheros/base-files/etc/hotplug.d/button/00-button
# https://forum.openwrt.org/viewtopic.php?pid=172110#p172110

. /lib/functions.sh

export PATH=/bin:/sbin:/usr/bin:/usr/sbin:/usr/local/bin:/usr/local/sbin

do_button () {
	local button

r10r

-include Settings.mk

# [ project ]
# ===========
default: all

# [ settings ]
# ============
BASE_DIR := $(realpath $(PWD))

FeodorFitsner

# Notes:
#   - Minimal appveyor.yml file is an empty file. All sections are optional.
#   - Indent each level of configuration with 2 spaces. Do not use tabs!
#   - All section names are case-sensitive.
#   - Section names should be unique on each level.

#---------------------------------#
#      general configuration      #
#---------------------------------#