title: How to restrict how many CPU cores Varnish uses?
body: <p>I have an 8 core server which will be running Varnish in front of a HTTP server, both on the same machine.</p>
  
  <p>How can I restrict Varnish to use no more than 4 cores?</p>
  
  <p>I have read of the worker pools in the documentation but it also says this:</p>
  
  <p>"Although Varnish threading model allows you to use multiple thread pools, we recommend you to do not modify this parameter. Based on our experience and tests, we have seen that 2 thread pools are enough. In other words, the performance of Varnish does not increase when adding more than 2 pools.</p>
  
  <p>Note If you run across the tuning advice that suggests to have a thread pool per CPU core, rest assured that this is old advice. We recommend to have at most 2 thread pools, but you may increase the number of threads per pool."</p>
  
  <p>So it seems 2 thread pools is sufficient. Does that mean only two CPU cores are used in that case?</p>
  
  <p>Searching through the documentation I so far haven't found a clear answer.</p>