Path: utzoo!mnetor!uunet!lll-winken!lll-tis!ames!ptsfa!pacbell!att-ih!ihnp4!ho95e!wcs From: wcs@ho95e.ATT.COM (Bill.Stewart.) Newsgroups: comp.unix.wizards Subject: Re: Shared Memory in BSD4.3 is lacking? Message-ID: <2033@ho95e.ATT.COM> Date: 4 Mar 88 19:53:37 GMT References: <9100@ism780c.UUCP> <2329@umd5.umd.edu> <2009@ho95e.ATT.COM> <2368@umd5.umd.edu> Reply-To: wcs@ho95e.UUCP (46323-Bill.Stewart.,2G218,x0705,) Organization: AT&T Bell Labs 46133, Holmdel, NJ Lines: 50 In article <2368@umd5.umd.edu> chris@trantor.umd.edu (Chris Torek) writes: :>In article <2329@umd5.umd.edu> I wrote: :>:System V shared memory is wrong. (Now there is a good flammable :In article <2009@ho95e.ATT.COM> wcs@ho95e.UUCP :>Ok, I'll flame! What's wrong with System V shared memory? [various good responses from Chris, Mike Ditto, and others] Yeah, I agree IPC really should be attached to the file system, though I'm not sure whether it should look like a regular file or like some variant on the "pipe" special file type or a character-special. Some of the "reasonable" implementations start to look appallingly like mmap(). :>I agree that the user interface is annoying, :(It feels like something IBM might have invented.) Ouch, that's getting nasty :-)! :Additionally, the total number of shared pages allowed is, I believe, :compiled into the kernel. It's at least configurable. On some architectures, with ancient or bizarre MMUs, it's tough to be flexible. :Finally, there is, it seems, no way to have sbrk and shm* :co-operate. This doesn't bother me much - sbrk is inherently dealing with a different memory space. But it *would* be nice to have malloc() able to use shm. :The future BSD shared memory will cure all of these :defects, or at least we think so.... If you do it right, it may be possible to write a System-V IPC emulation library, to preserve existing software. Bill Stewart, ho95c!wcs -- :[what *are* all those numbers in your name, anyway? :-) ] :(46323-Bill.Stewart,2G218,x0705,) writes: ^department ^room ^phone-extension The standard AT&T Bell Labs Comp. Center format for the gcos field is 11111-name(ABC123)1111 ^dept ^acct# ^printerbin The news software drops the account and printer bin. My department has extended the format a bit; we long ago added ",room-number,phone-extension" (see 4.1BSD passwd(5) - but we don't expand E and C to Evans and Cory); our current administrators have recently added a field. -- # Thanks; # Bill Stewart, AT&T Bell Labs 2G218, Holmdel NJ 1-201-949-0705 ihnp4!ho95c!wcs