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

zziuni

# source : http://code.google.com/p/natvpn/source/browse/trunk/stun_server_list
# A list of available STUN server.

stun.l.google.com:19302
stun1.l.google.com:19302
stun2.l.google.com:19302
stun3.l.google.com:19302
stun4.l.google.com:19302
stun01.sipphone.com
stun.ekiga.net

jackrusher

Hofstadter on Lisp

In the mid-80s, while reading through my roommate's collection of Scientific American back issues, I encountered this introduction to Lisp written by Douglas Hofstadter. I found it very charming at the time, and provide it here (somewhat illegally) for the edification of a new generation of Lispers.

In a testament to the timelessness of Lisp, you can still run all the examples below in emacs if you install these aliases:

(defalias 'plus #'+)
(defalias 'quotient #'/)
(defalias 'times #'*)
(defalias 'difference #'-)

deltamobile

package main

import (
        "fmt"
        "runtime"
        "time"
)

type Foo struct {
        name    string

panzi

#include <stdio.h>
#include <complex.h>
#define dc double complex
                                         dc
                                         Y(dc
                                           V,
                                      dc B,dc c){
                                        return
                               (cabs (V)<6)?(c?Y(V   *V+
                                 B,B,c-1):c):(2+c-4*cpow

cbednarski

import cv2

# Windows dependencies
# - Python 2.7.6: http://www.python.org/download/
# - OpenCV: http://opencv.org/
# - Numpy -- get numpy from here because the official builds don't support x64:
#   http://www.lfd.uci.edu/~gohlke/pythonlibs/#numpy

# Mac Dependencies
# - brew install python

tsiege

ANNOUNCEMENT

I have moved this over to the Tech Interview Cheat Sheet Repo and has been expanded and even has code challenges you can run and practice against!






\

kimenye

<?xml version="1.0" encoding="utf-8"?>
<manifest  xmlns:android="http://schemas.android.com/apk/res/android"
 android:versionCode="48513" android:versionName="2.11.301" package="com.whatsapp">
	<uses-permission android:name="android.permission.ACCESS_COARSE_LOCATION">
	</uses-permission>
	<uses-permission android:name="android.permission.ACCESS_FINE_LOCATION">
	</uses-permission>
	<uses-permission android:name="android.permission.ACCESS_NETWORK_STATE">
	</uses-permission>
	<uses-permission android:name="android.permission.ACCESS_WIFI_STATE">

keithshep

#!/usr/bin/env python -O

import argparse
import sys
import numpy
import h5py
import csv

class ColType:
    UNKNOWN = 1