Latency numbers every programmer should know

latency.md

CPU

• L1 cache reference 0.5 ns
• Branch mispredict 5 ns (on a bad CPU architecture you're pretty much screwed)
• L2 cache reference 7 ns
• Mutex lock/unlock 25 ns
• Main memory reference 100 ns
• Compress 1K bytes with Zippy 3,000 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

HDD

• Disk seek 10,000,000 ns
• Read 1 MB sequentially from disk 20,000,000 ns
• Send packet CA->Netherlands->CA 150,000,000 ns

SSD

• Disk seek 100,000 ns

By Jeff Dean