title: Are extended instruction sets (SSE, MMX) used in Linux kernel?
body: <p>Well, they bring (should bring at least) great increase in performance, isn’t it? </p>
  
  <p>So, I haven’t seen any Linux kernel sources, but ‘d love to ask: are they used somehow? (In this case – there must be some special “code-cap” for system that has no such instructions?)</p>