Numbers everyone should know

January 1, 2009

Jeff Dean, a brilliant engineer at Google, gave a talk a while ago listing the numbers every engineer should know. I copied these from here.

• L1 cache reference 0.5 ns
• Branch mispredict 5 ns
• L2 cache reference 7 ns
• Mutex lock/unlock 100 ns
• Main memory reference 100 ns
• Compress 1K bytes with Zippy 10,000 ns
• Send 2K bytes over 1 Gbps network 20,000 ns
• Read 1 MB sequentially from memory 250,000 ns
• Round trip within same datacenter 500,000 ns
• Disk seek 10,000,000 ns
• Read 1 MB sequentially from network 10,000,000 ns
• Read 1 MB sequentially from disk 30,000,000 ns
• Send packet CA->Netherlands->CA 150,000,000 ns

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Written by Pinku Posted in Technology