[net.unix-wizards] Virtual memory and UNIX

kh (03/16/83)

(We have 4.1bsd, but these questions are really about any virtual memory
 system.)
Two questions concerning virtual memory:

	(1) Does ld (the linking editor) take into any consideration
	the execution order of the various subroutines. The only
	paper I've ever read on the subject said that a little extra
	effort at load time can mean a BIG reduction in the number of
	page faults.

	(2) Why aren't at least some of the library routines in memory, instead
	of each program having its own copy?!? If "printf" alone were in
	memory, around 2K would be saved from each program that used it! And
	the number of page faults would also be lowered, since it would only
	be in physical memory once. I've heard (rumors) that VMS has such
	a feature, so it can't be too hard. This would be a great feature
	since it saves disk space, save memory space (hence speeds execution)
	and has the added bonus that you don't have to re-compile everything
	if you change a library routine.

Are there any plans for this kind of thing in future BSD's (or any other UNIX)?

					Kenny Hirsch
					duke!unc!kh
					kh.unc@UDel-Relay
					Chapel Hill, N.C.