Trying running perl -e 'while(1) { 1 }' sometime and see what that does to your CPU. :-)

As for how long to sleep, it depends on what you're doing: sometimes sleep(1) is enough, othertimes something a little (or a lot) longer is preferable.

Definitely something for you to experiment with, but the question you need to ask is how long can you afford to postpone another iteration of the loop?

Also, if you're feeling particularly nutty, you can use...

  while ( sleep(10) ) {
      ...
  }
[download]

... instead of the more traditional (?) ...

  while ( 1 ) {
      ...;
      sleep(10);
  }
[download]

Although the former ends up being as if sleep(10) was the first thing called inside the loop.

    --k.