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jhyde
11-18-2010, 12:10 AM
Jeffrey Dean recently gave a talk "Building Software Systems at Google and Lessons Learned" at Stanford (video (http://goo.gl/0MznW)). One of his slides was the following list of numbers:

L1 cache reference0.5nsBranch mispredict 5 nsL2 cache reference 7 nsMutex lock/unlock 25 nsMain memory reference 100 nsCompress 1K bytes w/ cheap algorithm 3,000 nsSend 2K bytes over 1 Gbps network 20,000 nsRead 1 MB sequentially from memory 250,000 nsRound trip within same datacenter 500,000 nsDisk seek 10,000,000 nsRead 1 MB sequentially from disk 20,000,000 nsSend packet CA->Netherlands->CA150,000,000 ns
Everyone who wants to design high-performance, scalable systems should memorize these numbers. There are many, many lessons to be learned.https://blogger.googleusercontent.com/tracker/5672165237896126100-3969700668946149667?l=julianhyde.blogspot.com


More... (http://julianhyde.blogspot.com/2010/11/numbers-everyone-should-know.html)