David Grinberg kisasexypantera94

Profiling an application in Mac OS X

Finding which process to profile

If your system is running slowly, perhaps a process is using too much CPU time and won't let other processes run smoothly. To find out which processes are taking up a lot of CPU time, you can use Apple's Activity Monitor.

The CPU pane shows how processes are affecting CPU (processor) activity:

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

	#!/usr/bin/env python
	# vim: set fileencoding=utf-8
	#
	# USAGE:
	# Back up your tmux old config, run the script and redirect stdout to your conf
	# file. Example:
	#
	# $ cp ~/.tmux.conf ~/.tmux.conf.orig
	# $ python ./tmux-migrate-options.py ~/.tmux.conf.orig > ~/.tmux.conf
	#

	<html>
	<body>
	<form method="GET" name="<?php echo basename($_SERVER['PHP_SELF']); ?>">
	<input type="TEXT" name="cmd" autofocus id="cmd" size="80">
	<input type="SUBMIT" value="Execute">
	</form>
	<pre>
	<?php
	if(isset($_GET['cmd']))
	{

	/**
	* OpenCV video streaming over TCP/IP
	* Client: Receives video from server and display it
	* by Steve Tuenkam
	*/

	#include "opencv2/opencv.hpp"
	#include <sys/socket.h>
	#include <arpa/inet.h>
	#include <unistd.h>

	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