Estimation

Performance

• Query with index should be around 1ms ~ 2ms

• One write should be around 5ms for SSD disk

CPU capability

• 1 CPU core can handle 200 operation

• Usually database server: 56 CPU cores -> 60 CPU cores or more

• 5-10 CPU cores should be enough without cache

• One database should be good enough to handle the load

Cache performance

• Memcache or Rediss usually are cluster, and usually one operation takes 0.1ms or less.

  • 1 CPU cores => 5000-10000 requests

  • 20-40 CPU cores => 200K requests (one machine)

QPS and concurrency

• Defined inside Little's law

• For example, if a server has a QPS of 20K and 10ms average response time.

• Then the concurrency number will be 200.