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

abelsonlive

require("rjson")

#generate urls to scrape
#I determined the lowest and highest unique ids 
#by looking at the page that had just the coordinates

root.url <- "http://a841-tfpweb.nyc.gov/bikeshare/get_point_info?point="
id<- seq(11992,12404, by=1) 
urls <- paste(root.url, id, sep="")

paulfitz

default:
	asciidoc tdiff_spec_draft.txt