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

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

rtgibbons

#!/bin/bash

unload() {
	kextstat | grep "org.virtualbox.kext.VBoxUSB" > /dev/null 2>&1 && sudo kextunload -b org.virtualbox.kext.VBoxUSB
	kextstat | grep "org.virtualbox.kext.VBoxNetFlt" > /dev/null 2>&1 && sudo kextunload -b org.virtualbox.kext.VBoxNetFlt
	kextstat | grep "org.virtualbox.kext.VBoxNetAdp" > /dev/null 2>&1 && sudo kextunload -b org.virtualbox.kext.VBoxNetAdp
	kextstat | grep "org.virtualbox.kext.VBoxDrv" > /dev/null 2>&1 && sudo kextunload -b org.virtualbox.kext.VBoxDrv
}

load() {

nstielau

# Send a metric to statsd from bash
#
# Useful for:
#   deploy scripts (http://codeascraft.etsy.com/2010/12/08/track-every-release/)
#   init scripts
#   sending metrics via crontab one-liners
#   sprinkling in existing bash scripts.
#
# netcat options: 
#   -w timeout If a connection and stdin are idle for more than timeout seconds, then the connection is silently closed.  

lkraider

// avcodec_sample.0.5.0.c

// Original source:
// http://web.me.com/dhoerl/Home/Tech_Blog/Entries/2009/1/22_Revised_avcodec_sample.c.html
//
// A small sample program that shows how to use libavformat and libavcodec to
// read video from a file.
//
// This version is for the 0.4.9+ release of ffmpeg. This release adds the
// av_read_frame() API call, which simplifies the reading of video frames