From owner-freebsd-hackers Thu Feb 11 00:23:18 1999 Return-Path: Received: (from majordom@localhost) by hub.freebsd.org (8.8.8/8.8.8) id AAA12174 for freebsd-hackers-outgoing; Thu, 11 Feb 1999 00:23:18 -0800 (PST) (envelope-from owner-freebsd-hackers@FreeBSD.ORG) Received: from iquest3.iquest.net (iquest3.iquest.net [209.43.20.203]) by hub.freebsd.org (8.8.8/8.8.8) with SMTP id AAA12167 for ; Thu, 11 Feb 1999 00:23:17 -0800 (PST) (envelope-from toor@y.dyson.net) Received: (qmail 16716 invoked from network); 11 Feb 1999 08:23:08 -0000 Received: from dyson.iquest.net (HELO y.dyson.net) (198.70.144.127) by iquest3.iquest.net with SMTP; 11 Feb 1999 08:23:08 -0000 Received: (from root@localhost) by y.dyson.net (8.9.1/8.9.1) id DAA03550; Thu, 11 Feb 1999 03:23:08 -0500 (EST) Message-Id: <199902110823.DAA03550@y.dyson.net> Subject: Re: portability of shm, mmap, pipes and socket IPC In-Reply-To: <199902102350.PAA01211@dingo.cdrom.com> from Mike Smith at "Feb 10, 99 03:50:51 pm" To: mike@smith.net.au (Mike Smith) Date: Thu, 11 Feb 1999 03:23:07 -0500 (EST) Cc: dyson@iquest.net, dg@root.com, tlambert@primenet.com, dillon@apollo.backplane.com, kuku@gilberto.physik.RWTH-Aachen.DE, hackers@FreeBSD.ORG From: "John S. Dyson" Reply-To: dyson@iquest.net X-Mailer: ELM [version 2.4ME+ PL38 (25)] MIME-Version: 1.0 Content-Type: text/plain; charset=US-ASCII Content-Transfer-Encoding: 7bit Sender: owner-freebsd-hackers@FreeBSD.ORG Precedence: bulk X-Loop: FreeBSD.ORG Mike Smith said: > > David Greenman said: > > > >> >:The overall size of the shared memory segment is limited to that > > > >> >: which can fit in the kernels virtual address space; this > > > >> >: artificially restricts the maximum size. > > > >> > > > >> That isn't true and hasn't been true for several years in FreeBSD. > > > > > > > >Are you sure? > > > > > > Yes, I'm quite sure. > > > > > DG's statement is accurate. I removed that very artificial restriction over > > 2 yrs ago. There is no reason to use KVA space for data that the kernel never > > needs to see. Correcting that deficit was pretty much on my list as soon as > > I saw that problem when FreeBSD made it an official part of the distribution. > > Hmm, so does that mean that the shared memory pages can be paged out? > And if so, should we be removing the SHMMAXPGS kernel option (since our > current shared memory profile is woefully inadequate for most uses)? > Shared memory pages *can* be paged out. There are policy issues that DG and others (maybe including you) need to evaluate before deciding that SHMMAXPGS isn't something that is desirable. I suspect that SHMMAXPGS is pretty much redundant, but... :-). -- John | Never try to teach a pig to sing, dyson@iquest.net | it makes one look stupid jdyson@nc.com | and it irritates the pig. To Unsubscribe: send mail to majordomo@FreeBSD.org with "unsubscribe freebsd-hackers" in the body of the message