Read sequentially from 1 Gbps Ethernet at 100 MB/s
以 100 MB/s 的速度从 1 Gbps 以太网顺序读取
Read sequentially from SSD at 1 GB/s
以 1 GB/s 的速度从 SSD 顺序读取
Read sequentially from main memory at 4 GB/s
以 4 GB/s 的速度从主内存顺序读取
6-7 world-wide round trips per second
每秒 6-7 次全球往返
2,000 round trips per second within a data center
数据中心内每秒 2,000 次往返
Latency numbers visualized
Minute
1 2 3 4
L1 cache reference 0.5 s One heart beat (0.5 s) Branch mispredict 5 s Yawn L2 cache reference 7 s Long yawn Mutex lock/unlock 25 s Making a coffee
Hour
1 2
Main memory reference 100 s Brushing your teeth Compress 1K bytes with Zippy 50 min One episode of a TV show (including ad breaks)
Day
1
Send 2K bytes over 1 Gbps network 5.5 hr From lunch to end of work day
Week
1 2 3 4
SSD random read 1.7 days A normal weekend Read 1 MB sequentially from memory 2.9 days A long weekend Round trip within same datacenter 5.8 days A medium vacation Read 1 MB sequentially from SSD 11.6 days Waiting for almost 2 weeks for a delivery
Year
1 2 3
Disk seek 16.5 weeks A semester in university Read 1 MB sequentially from disk 7.8 months Almost producing a new human being The above 2 together 1 year
Decade
1
Send packet CA->Netherlands->CA 4.8 years Average time it takes to complete a bachelor's degree