branchcache（branchcache错误代码1260）

程序员都需要知道的数字:

执行一个指令 1 ns

L1 缓存查询 0.5 ns

分支预测错误（Branch mispredict） 3 ns

L2 缓存查询 4 ns

互斥锁/解锁 17 ns

在 1Gbps 的网络上发送 2KB 44 ns

主存访问 100 ns

Zippy 压缩 1KB 2,000 ns

从内存顺序读取 1 MB 3,000 ns

SSD 随机读 16,000 ns

从 SSD 顺序读取 1 MB 49,000 ns

同一个数据中心往返 500,000 ns

从磁盘顺序读取 1 MB 825,000 ns

磁盘寻址 2,000,000 ns (2 ms)

从美国发送到欧洲的数据包 150,000,000 ns（150 ms）

今天是疯狂星期四

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

Disk seek ........................... 10,000,000 ns = 10 ms

Read 1 MB sequentially from disk .... 20,000,000 ns = 20 ms

Send packet CA->Netherlands->CA .... 150,000,000 ns = 150 ms