Date: Mon, 5 Jan 1998 23:37:05 -0800 (PST) From: Julian Elischer <julian@whistle.com> To: John Dyson <dyson@freebsd.org> Cc: cvs-committers@freebsd.org, cvs-all@freebsd.org, cvs-sys@freebsd.org Subject: John's latest VM commit. Message-ID: <Pine.BSF.3.95.980105233239.7998A-100000@current1.whistle.com> In-Reply-To: <199801060526.VAA08011@freefall.freebsd.org>
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Kirk told me a few years ago that he was seriously considering merging the vm-object and vnode strucures so that one BECAME the other. Is this a stupid idea? In his estimation, they contained many of the same fiedls which simply meant duplication of information, an danother place where things could get out of sync. Of course this was 5 years ago so you may already have removed much of the duplication. julian On Mon, 5 Jan 1998, John Dyson wrote: > dyson 1998/01/05 21:26:20 PST > Log: > Make our v_usecount vnode reference count work identically to the > original BSD code. The association between the vnode and the vm_object > no longer includes reference counts. The major difference is that > vm_object's are no longer freed gratuitiously from the vnode, and so > once an object is created for the vnode, it will last as long as the > vnode does. > > When a vnode object reference count is incremented, then the underlying > vnode reference count is incremented also. The two "objects" are now > more intimately related, and so the interactions are now much less > complex. > > When vnodes are now normally placed onto the free queue with an object still > attached. The rundown of the object happens at vnode rundown time, and > happens with exactly the same filesystem semantics of the original VFS > code. There is absolutely no need for vnode_pager_uncache and other > travesties like that anymore. > > A side-effect of these changes is that SMP locking should be much simpler, > the I/O copyin/copyout optimizations work, NFS should be more ponderable, > and further work on layered filesystems should be less frustrating, because > of the totally coherent management of the vnode objects and vnodes. >
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