Swap space size

[Richard Todd]

gerson at parc.xerox.com (Dan Gerson) writes:
>I have about 200MB of disk space available for A/UX, and am wondering
>how large of a swap space to allocate.  I plan on running X11 and Emacs,
>and plan to do a fair amount of compilation.  At work, we use 140MB
>swap partitions, but then, we do extensive DB and Lisp work.  Any
>suggestions on how much swap space makes sense for A/UX?  I'm thinking
>somewhere between 40MB and 60MB.

40-60M?  Sounds a little *high*, if you ask me.  How much RAM do you have?
If, like most people, you don't have more than 8M, there's really not much
point in having more than, say 24M (3*8M) of swap space.  With 8M physical
memory (roughly 6-6.5M free after subtracting kernel space) and 24M swap,
this would give you a max virtual memory total of 30M.  Trust me, if you're 
actually trying to actively use this much VM in a machine with only 8M RAM,
you're gonna regret it, as your system will be in a state of Perpetual Paging.

  On my system, I've got 20M of swap and 8M of physical memory, and don't 
recall ever running out.  I regularly run X11 and Emacs (note to memory 
usage aficionados--if you're running the MacOS environment under A/UX with 
its default memory allocations, it's at least as much of a memory hog as X11
is), and do big compiles with GCC as well as the odd Lisp program under Yale's
port of the T language to A/UX.  Right now, I'm under the MacOS emulator, with
a couple of CommandShell windows running, plus nn and Emacs, and my system-
monitor program shows 9940K VM in use.  

  My advice is, only reserve 20M to swap, and add the rest to your filesystem
space, since you *always* need more space to hold files :-).  

  Other helpful hint: If you've got more than one drive, you might consider
having a, say 10M swap partition on each drive instead of a big 20M swap 
partition on one drive.  Splitting swap space between multiple drives seems
to help performance.  (Yes, A/UX does support multiple swap partitions; check
out the man page for swap(1) for more info).  
--
Richard Todd	rmtodd at uokmax.ecn.uoknor.edu  rmtodd at chinet.chi.il.us
	rmtodd at servalan.uucp
Motorola Skates On Intel's Head!