streams in 5.4

[George Bogatko]

HI:

	I'm working on a Pyramid MIserver, AKA AT&T70**, which is currently
running OSx, which is BSD with enough stuff added to make it look like
System V.  (A short, inaccurate discription, not really good flame
material, so.......)

	They are soon to come out with System 5.4 however, which prompts
this question.

	How much KERNEL space does streams take up in 5.4.  More to the point,
when the streams tunables are increased in 5.4, how much extra ram does the
kernel steal away from user space.  I have looked in the 3B manuals, and
they seem to indicate that streams are "free", but when I recently activated
streams on a 3B (running 5.3.2), user space decreased (28 headers cost
.8 to one meg).

	I can't really RTFM here because we don't have any 5.4 manuals
around. (no machines either)

	The reason I need to know this is because the group I work with
is proposing mega-systems running on the Pyramid/ATT machine.  Numbers
like 500 to 1000 users on one (big, groaning) machine.  Now I've read
that in 5.4, everything uses streams; tty's, pipes, all the stuff that
didn't really cost a lot of user space in 5.3.  BUT, if an application
currently uses one or two pipes, a tty connection, and a few other
gadgets, this could translate into 3 or 4 streams per user.  Multiplied
by a potential 1000 user system, this is 3000 or 4000 streams, each
with a stream head and tail, plus any modules, plus any other stuff
needed by the kernel.

	How much space will 4000+ stream units consume?  

GB