title: Redis - correlation between QPS, response time, number of connections, response size and network connection speed
body: <p>As a follow up to my previous question, <a href="https://stackoverflow.com/questions/27268182/how-does-redis-achieve-the-high-throughput-and-performance/27269269#27269269">How does Redis achieve the high throughput and performance?</a></p>
  
  <p>I have the following questions</p>
  
  <p>I have seen Redis in action and is impressed and awed at its capacity. Want to understand more about this magic. I have seen that response times are of the order 5ms even at high QPS (1kps) when Redis box and querying box are closer. Response time goes up to 50ms when they are geographically farther (same Datacentre vs different datacentre). Is this just network latency or Redis has to maintain some overhead till entire data is flushed out.</p>
  
  <p>Can number of connections affect Redis throughput? Imagine that Redis is able to respond in 500 micro seconds for every request. And imagine there are 1000 different requests at a give instance in time from 1000 different client connections. Will the last request take 500muSec * 1000 = 500ms?</p>
  
  <p>Can response size have an affect here? Imagine each response is of the order of size 100 KB, TCP connection on the Redis has to wait till the last packet is delivered and if the network connection is slow, will it slowdown Redis?</p>