title: Does a thread waiting on IO also block a core?
body: <p>In the synchronous/blocking model of computation we usually say that a thread of execution will wait (be <em>blocked</em>) while it waits for an IO task to complete.</p>
  
  <p>My question is simply will this usually cause the CPU core executing the thread to be idle, or will a thread waiting on IO usually be context switched out and put into a waiting state until the IO is ready to be processed?</p>