On Fri, 26 Jun 1998 08:20:40 +1000, Richard Gooch
<Richard.Gooch@atnf.CSIRO.AU> said:
>> With a fcntl(fd, F_SETSIG, signum), you can tell the kernel to send a
>> realtime signal with the specified signum instead of SIGIO for all
>> unblock events on that file descriptor. The signal will be queued with
>> the fd as an argument to the signal handler. If the signal queue
>> overflows, the kernel will deliver a generic SIGIO to let the
>> application know it should select() against all fds to find which ones
>> may have missed a realtime signal.
> But once again we have a non-standard hack for Linux. If we do that
> then as far as I'm concerned, we may as well implement "readiness
> queues". Anyway, I'm pursuing a scalable solution that works for
> other UNIX systems.
The only real standard interfaces under Linux are O(n) anyway. If
you're poll()ing on 10,000 socket fds, there's a limit to how fast you
can conceivably go. posix.1b signals are standard; SIGIO is standard;
combining the two is an obvious way to implement completion queues
with a minimum of non-standardness. It's not _completely_ standard,
but I don't see any fully standard and scalable interface alternatives
right now.
--Stephen
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