计算机系统中延迟时间比较

最新推荐文章于 2021-07-25 07:12:42 发布

转载最新推荐文章于 2021-07-25 07:12:42 发布 · 707 阅读

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本文详细列举了从L1缓存引用到网络延迟的各种计算机操作所需的时间，覆盖了内存访问、磁盘读取、网络通信等多个层面，为理解系统性能瓶颈提供量化参考。

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L1 cache reference ..................................... 0.5 ns
Branch mispredict ........................................ 5 ns
L2 cache reference ....................................... 7 ns
Mutex lock/unlock ....................................... 25 ns
Main memory reference .................................. 100 ns
Compress 1K bytes with Zippy ......................... 3,000 ns =   3 µs
Send 2K bytes over 1 Gbps network ................... 20,000 ns =  20 µs
SSD random read .................................... 150,000 ns = 150 µs
Read 1 MB sequentially from memory ................. 250,000 ns = 250 µs
Round trip within same datacenter .................. 500,000 ns = 0.5 ms
Read 1 MB sequentially from SSD .................. 1,000,000 ns =   1 ms
Network delay between two Shanghai datacenters ... 1,000,000 ns =   1 ms
Disk seek ....................................... 10,000,000 ns =  10 ms
Read 1 MB sequentially from disk ................ 20,000,000 ns =  20 ms
Network delay from Beijing to Shanghai .......... 30,000,000 ns =  30 ms
Send packet CA->Netherlands->CA ................ 150,000,000 ns = 150 ms