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

MohamedAlaa

tmux shortcuts & cheatsheet

start new:

tmux

start new with session name:

tmux new -s myname

mikhailov

# Nginx+Unicorn best-practices congifuration guide. Heartbleed fixed.
# We use latest stable nginx with fresh **openssl**, **zlib** and **pcre** dependencies.
# Some extra handy modules to use: --with-http_stub_status_module --with-http_gzip_static_module
#
# Deployment structure
#
# SERVER:
#  /etc/init.d/nginx                             (1. nginx)
#  /home/app/public_html/app_production/current  (Capistrano directory)
#

pwenzel

#!/bin/bash

while [ 1 ]
do
    rsync -avz --partial source dest
    if [ "$?" = "0" ] ; then
        echo "rsync completed normally"
        exit
    else
        echo "Rsync failure. Backing off and retrying..."

KartikTalwar

The fastest remote directory rsync over ssh archival I can muster (40MB/s over 1gb NICs)

This creates an archive that does the following:

rsync (Everyone seems to like -z, but it is much slower for me)

• a: archive mode - rescursive, preserves owner, preserves permissions, preserves modification times, preserves group, copies symlinks as symlinks, preserves device files.
• H: preserves hard-links
• A: preserves ACLs

Tasssadar

diff --git a/arch/arm/Kconfig b/arch/arm/Kconfig
index 3c3b868..5903cec 100644
--- a/arch/arm/Kconfig
+++ b/arch/arm/Kconfig
@@ -1993,6 +1993,32 @@ config ATAGS_PROC
 	  Should the atags used to boot the kernel be exported in an "atags"
 	  file in procfs. Useful with kexec.
 
+config KEXEC_HARDBOOT
+	bool "Support hard booting to a kexec kernel"

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

XVilka

THIS GIST WAS MOVED TO TERMSTANDARD/COLORS REPOSITORY.

PLEASE ASK YOUR QUESTIONS OR ADD ANY SUGGESTIONS AS A REPOSITORY ISSUES OR PULL REQUESTS INSTEAD!

justecorruptio

M[16],X=16,W,k;main(){T(system("stty cbreak")
);puts(W&1?"WIN":"LOSE");}K[]={2,3,1};s(f,d,i
,j,l,P){for(i=4;i--;)for(j=k=l=0;k<4;)j<4?P=M
[w(d,i,j++)],W|=P>>11,l*P&&(f?M[w(d,i,k)]=l<<
(l==P):0,k++),l=l?P?l-P?P:0:l:P:(f?M[w(d,i,k)
]=l:0,++k,W|=2*!l,l=0);}w(d,i,j){return d?w(d
-1,j,3-i):4*i+j;}T(i){for(i=X+rand()%X;M[i%X]
*i;i--);i?M[i%X]=2<<rand()%2:0;for(W=i=0;i<4;
)s(0,i++);for(i=X,puts("\e[2J\e[H");i--;i%4||
puts(""))printf(M[i]?"%4d|":"    |",M[i]);W-2

miguelfrde

Arch Linux installation (preinstalled Windows 8.1 dual boot)

Before

1. Disable Windows Fast-Startup
2. Disable Secure Boot

Partitioning