true asynchronous I/O in Unix

[A. Lester Buck]

I have been asked to study how various (mainly realtime) vendors have added
asynchronous I/O to their versions of Unix.  I am interested in existing
or proposed implementations, or any literature on the subject.  I would also
appreciate receiving any personal suggestions for how you think async I/O
should look.  I know lightweight process support a la Mach will someday make
this issue moot, but I am looking for simple and modular solutions that
would be useful today.

To begin, I know some details of the following:

RTU     Uses Asynchronous System Traps as described in "Writing a
        UNIX Device Driver".  Kernel implementation of medium difficulty.

Ultrix  Uses an nbuf scheme, with ioctl interface and select.  Kernel
        implementation relatively easy.


I will summarize if there is any interest.

Thanks alot!

-- 
A. Lester Buck     buck at siswat.lonestar.org  ...!texbell!moray!siswat!buck