Credit to Jeff Dean: http://research.google.com/people/jeff/
Latency | Unit (ns) | |
---|---|---|
L1 cache reference | 0.5 | |
Branch mispredict | 5 | |
L2 cache reference | 7 | 14x L1 cache |
Mutex lock/unlock | 25 | |
Main memory reference | 100 | 20x L2 cache |
Compress 1K bytes with Zippy | 3,000 | |
Send 1K bytes over 1 Gbps network | 10,000 | 0.01 ms |
Read 4K randomly from SSD* | 150,000 | 0.15ms |
Read 1 MB sequentially from memory | 250,000 | 0.25ms |
Round trip within same datacenter | 500,000 | 0.5ms |
Read 1 MB sequentially from SSD* | 1,000,000 | 1 ms 4X memory |
Disk seek | 10,000,000 | 10 ms 20x datacenter roundtrip |
Read 1 MB sequentially from disk | 20,000,000 | 80x memory, 20X SSD |
Send packet CA->Netherlands->CA | 150,000,000 | 150ms |
Notes
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1 ns = 10^9 seconds
1 ms = 10^3 seconds
* Assuming ~1GB/sec SSD
-----
1 ns = 10^9 seconds
1 ms = 10^3 seconds
* Assuming ~1GB/sec SSD