/dev/poll vs. sigio enhancements

[Daniel R. Kegel]

I've updated http://www.kegel.com/c10k.html with a description
of (and link to man page for) Solaris' new /dev/poll interface,
a way to avoid the overhead of continually building a list of
pollfd's to pass to poll().  According to Sun, at 750 fd's,
this has 10% of the overhead of poll().

sct has a set of changes in 2.3.x that let you avoid the overhead of
poll() in a different way, using the realtime signal queue to carry
fd state change events.

It might be good for Linux to support the /dev/poll scheme also.
It's easier interface to document and use than the signal-based one, 
which is a bit complicated to get right.
This would also make it easier for Solaris programs that use the /dev/poll 
interface to migrate to Linux.  
I'll let sct speak to how icky it would be to implement /dev/poll...
I'm just speaking from a kernel user's point of view.

- Dan