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Latency And Throughput

Latency and Throughput are the two important measures to measure the performance of the system.

Latency​

Latency is specifically how long does it take to reach from one point to another point in the system.

The time it takes for a certain operation to complete in a system. Most often this measure is a time duration, like milliseconds or seconds. You should know these orders of magnitude:

  • Reading 1 MB from RAM: 250us (0.25 ms)
  • Reading 1 MB from SSD: 1,000us (1 ms)
  • Transfer 1 MB from Network: 10,000us (10 ms)
  • Reading 1 MB from HDD: 20,000us (20 ms)
  • Inter-Continental Round Trip: 150,000us (150 ms)

Throughput​

The number of operations that a system can handle properly per time unit. For instance the throughput of a server can often be measured in requests per second (RPS or QPS).