bogatko@lzga.ATT.COM (George Bogatko) (08/07/90)
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