From owner-cvs-sys Tue Jan 6 01:11:05 1998 Return-Path: Received: (from root@localhost) by hub.freebsd.org (8.8.7/8.8.7) id BAA19111 for cvs-sys-outgoing; Tue, 6 Jan 1998 01:11:05 -0800 (PST) (envelope-from owner-cvs-sys) Received: from implode.root.com (implode.root.com [198.145.90.17]) by hub.freebsd.org (8.8.7/8.8.7) with ESMTP id BAA18859; Tue, 6 Jan 1998 01:05:52 -0800 (PST) (envelope-from root@implode.root.com) Received: from implode.root.com (localhost [127.0.0.1]) by implode.root.com (8.8.5/8.8.5) with ESMTP id BAA27275; Tue, 6 Jan 1998 01:05:02 -0800 (PST) Message-Id: <199801060905.BAA27275@implode.root.com> To: Julian Elischer cc: "John S. Dyson" , cvs-committers@FreeBSD.ORG, cvs-all@FreeBSD.ORG, cvs-sys@FreeBSD.ORG Subject: Re: John's latest VM commit. From: David Greenman Reply-To: dg@root.com Date: Tue, 06 Jan 1998 01:05:02 -0800 Sender: owner-cvs-sys@FreeBSD.ORG X-Loop: FreeBSD.org Precedence: bulk >>> It would probably be a good thing to make all caching in our system VM object >>> based. Then buffers will degrade into a structure used to communicate with >>> I/O devices. I would not like to see the terrible mess that SVR4 has, with >>> various types of vnode like structures in order to represent swap, filesystem, >>> device files. >>But every VM object needs an associated VNODE that represents the methods >>and data needed to access teh real backing store. I said: > Actually, this isn't true. Most VM objects in the system are not vnode >objects and thus have no vnode associated with them. Most of the vnode >objects are actually containers for 'anonymous' memory that either has >no backing ('default pager') or is swap backed. It could be argued that After thinking about what I said for a bit, I think I might be exagerating a little - on some systems where the vnode/object cache is sufficiently large, you could easily have more of those than default/swap objects. It depends on the processes - how many, memory mappings, etc., and how many cached files are in the system. It would be more accurate to say simply that there are a sizeable number of non-vnode objects... -DG David Greenman Core-team/Principal Architect, The FreeBSD Project