Subject: Re: kern/3537: Idea for SysV IPC Messages improvement
To: None <>
From: der Mouse <mouse@Rodents.Montreal.QC.CA>
List: netbsd-bugs
Date: 04/26/1997 08:41:51
> 	If I recall, AIX added yet another syscall that is select()
> 	plus additional argument(s) for message queues. This is kind of
> 	icky.


> 	It just occurred to me, while looking at how SIGIO is
> 	implemented, that a similar idea could be implemented for
> 	message queues.  [...]

Could be...but is this the right way to do it?  I don't like the idea
of having to take signal delivery overhead just to be notified of input
on a message queue.

Here's another idea; I have no idea how easy it would be: create a
special device driver.  To select on a message queue, you open this
device, do some operation (an ioctl?) to associate that instance of the
device with the desired message queue, and then select on the file
descriptor.  (The device would never generate any input; its only value
would be select()/poll().  Most of its driver routines would be stubs;
only the select routine, plus whatever is necessary to support the
association of a message queue with each open fd onto the device, would
actually be present.)

					der Mouse

		     7D C8 61 52 5D E7 2D 39  4E F1 31 3E E8 B3 27 4B