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

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!

ryanchang

LLDB Cheat Sheet

A complete gdb to lldb command map.

Print out

• Print object

(lldb) po responseObject
(lldb) po [responseObject objectForKey@"state"]

• p - Print primitive type

bzerangue

Verify and Repair Disk Permissions via Terminal (Mac OS X)

Verify Permissions

diskutil verifyPermissions /

Repair Permissions

diskutil repairPermissions /

pokev25

# Install tmux 2.8 on Centos

# install deps
yum install gcc kernel-devel make ncurses-devel

# cd src
cd /usr/local/src

# DOWNLOAD SOURCES FOR LIBEVENT AND MAKE AND INSTALL
curl -LO https://github.com/libevent/libevent/releases/download/release-2.1.8-stable/libevent-2.1.8-stable.tar.gz

yossorion

What I Wish I'd Known About Equity Before Joining A Unicorn

Disclaimer: This piece is written anonymously. The names of a few particular companies are mentioned, but as common examples only.

This is a short write-up on things that I wish I'd known and considered before joining a private company (aka startup, aka unicorn in some cases). I'm not trying to make the case that you should never join a private company, but the power imbalance between founder and employee is extreme, and that potential candidates would

CodaFi

// swift -Xfrontend -debug-constraints

infix operator ^&&^ : LogicalConjunctionPrecedence
infix operator ^||^ : LogicalConjunctionPrecedence

struct T{}
struct F{}

func λ(_ f : (T) -> ()) {
  print("true")

tkersey

New Build System Tricks

Command Line

# enable internal menu
defaults write com.apple.dt.Xcode ShowDVTDebugMenu -bool YES

alias xcbuild=$(xcode-select -p)/../SharedFrameworks/XCBuild.framework/Versions/A/Support/xcbuild

manigandham

Various search databases and backends as alternatives to Elasticsearch.

Rust

• Sonic - github.com/valeriansaliou/sonic - lightweight & schema-less search backend
• Tantivy - github.com/quickwit-oss/tantivy - full-text search engine library inspired by Apache Lucene
• Toshi - github.com/toshi-search/Toshi - search engine built on top of Tantivy
• Bayard - github.com/mosuka/bayard - search engine built on top of Tantivy
• Meilisearch - github.com/meilisearch/meilisearch - fast and full-featured search engine