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jeff-dean's-useful-numbers

CREATED BY chris • LAST EDITED BY chris 5809 days AGO

Jeff Dean's highly useful (napkin-sketching) numbers:

- 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

~~Rescued~~ Copied from the depths of Google Moderator.

I haven't quite made the transition to adopting the nanosecond as reference timespan yet; therefore, in operations per second (caveat interpretor):

- L1 cache reference: 2g/s
- L2 cache reference: 150m/s
- Main memory reference: 10m/s
- Disk seek: 100/s
- Read 1 MB sequentially from memory: 4000/s
- Read 1 MB sequentially from network: 100/s
- Read 1 MB sequentially from disk: 33/s