numbers
PUBLIC记住一些数据，有助于防诈骗
生命窗口
宇宙出现时间 130亿
地球出现时间 46亿
太阳剩余寿命 50亿
延迟
| Latency Comparison Numbers (~2012) | ||||
|---|---|---|---|---|
| L1 cache reference | 0.5 ns | |||
| Branch mispredict | 5 ns | |||
| L2 cache reference | 7 ns | 14x L1 cache | ||
| Mutex lock/unlock | 25 ns | |||
| Main memory reference | 100 ns | 20x L2 cache, 200x L1 cache | ||
| Compress 1K bytes with Zippy | 3,000 ns | 3 us | ||
| Send 1K bytes over 1 Gbps network | 10,000 ns | 10 us | ||
| Read 4K randomly from SSD* | 150,000 ns | 150 us | ~1GB/sec SSD | |
| Read 1 MB sequentially from memory | 250,000 ns | 250 us | ||
| Round trip within same datacenter | 500,000 ns | 500 us | ||
| Read 1 MB sequentially from SSD* | 1,000,000 ns | 1,000 us | 1 ms | ~1GB/sec SSD, 4X memory |
| Disk seek | 10,000,000 ns | 10,000 us | 10 ms | 20x datacenter roundtrip |
| Read 1 MB sequentially from disk | 20,000,000 ns | 20,000 us | 20 ms | 80x memory, 20X SSD |
| Send packet CA->Netherlands->CA | 150,000,000 ns | 150,000 us | 150 ms |
Notes
1 ns = 10^-9 seconds
1 us = 10^-6 seconds = 1,000 ns
1 ms = 10^-3 seconds = 1,000 us = 1,000,000 ns
Credit
By Jeff Dean: http://research.google.com/people/jeff/
Originally by Peter Norvig: http://norvig.com/21-days.html#answers
Contributions
‘Humanized’ comparison: https://gist.github.com/hellerbarde/2843375
Visual comparison chart:
others
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- IPC性能 https://github.com/goldsborough/ipc-bench