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

Haskell

yonedaLemma = Iso (flip fmap) ($ id)

seboudry

Latency numbers every programmer should know

L1 cache reference ......................... 0.5 ns
Branch mispredict ............................ 5 ns                     on recent CPU
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 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 4X memory

hsribei

Can NAT traversal be Tor's killer feature?

tl;dr: how about a virtual global flat LAN that maps static IPs to onion addresses?

[We all know the story][1]. Random feature gets unintentionally picked up as the main reason for buying/using a certain product, despite the creator's intention being different or more general. (PC: spreadsheets; Internet: porn; smartphones: messaging.)

knutwalker

package example.statemachine

import scalaz.{State, Scalaz}, Scalaz._

object FSM {
  def apply[I, S](f: PartialFunction[(I, S), S]): FSM[I, S] =
    new FSM((i, s) => f.applyOrElse((i, s), (_: (I, S)) => s))

  private def states[S, O](xs: List[State[S, O]]): State[S, List[O]] =
    xs.sequence[({type λ[α]=State[S, α]})#λ, O]

rygorous

Why do compilers even bother with exploiting undefinedness signed overflow? And what are those
mysterious cases where it helps?

A lot of people (myself included) are against transforms that aggressively exploit undefined behavior, but
I think it's useful to know what compiler writers are accomplishing by this.

TL;DR: C doesn't work very well if int!=register width, but (for backwards compat) int is 32-bit on all
major 64-bit targets, and this causes quite hairy problems for code generation and optimization in some
fairly common cases. The signed overflow UB exploitation is an attempt to work around this.

cube-drone

Automation for the People

Long ago, the first time I read "The Pragmatic Programmer", I read some advice that really stuck with me.

"Don't Use Manual Procedures".

This in the chapter on Ubiquitous Automation. To summarize, they want you to automate all the things.

The trouble was that I hadn't much of an idea how to actually go

marcan

#!/boot/bzImage

# Linux kernel userspace initialization code, translated to bash
# (Minus floppy disk handling, because seriously, it's 2017.)
# Not 100% accurate, but gives you a good idea of how kernel init works
# GPLv2, Copyright 2017 Hector Martin <marcan@marcan.st>
# Based on Linux 4.10-rc2.

# Note: pretend chroot is a builtin and affects the current process
# Note: kernel actually uses major/minor device numbers instead of device name

pjagielski

(ns talk
  (:require [overtone.core :refer :all]
            [clojure.java.io :as io]))

;; Overtone by Sam Aaron & Jeff Rose
;; https://github.com/overtone/overtone

(definst da-funk [freq 440 dur 1.0 amp 1.0 cutoff 1700 boost 6 dist-level 0.015]
   (let [env (env-gen (adsr 0.3 0.7 0.5 0.3) (line:kr 1.0 0.0 dur) :action FREE)
         filter-env (+ (* freq 0.15)

levelsio

<?
	//
	// [ BUY BTC & ETH DAILY ON BITSTAMP ]
	// by @levelsio
	//
	// 2017-08-23
	//
	// 1) buy $40/day BTC
	// 2) buy $10/day ETH
	//