Adam Glass <adamg@microsoft.com> writes:

> 
> From what source do you expect the huge number of callouts at once that
> justify this kind of structure, i.e what application or application mix?

I think you and Chris are making the same mistake -- looking only at
how callouts are currently used.  Callouts are currently used very
sparsely, precisely because they are very inefficient.  It would be a
win to use them in certain places where they are not currently.  The
specific application that brought this up is TCP retransmission
timers, which are currently quite inefficient when the number of
connections is large, and always fairly imprecise.

The point is to make callouts cheap enough that they can be used
wherever there is a reasonable need for more precise timing.