:On Wed, 18 Aug 1999, Poul-Henning Kamp wrote:
:
:> Matt doesn't represent the FreeBSD project, and even if he rewrites
:> the VFS subsystem so he can understand it, his rewrite would face
:> considerable resistance on its way into FreeBSD. I don't think
:> there is reason to rewrite it, but there certainly are areas
:> that need fixing.
:
:You are misinformed as far as I know.. From discussions I saw, th
:main architect of a VFS rewrite would be Kirk, and Matt would be acting as
:Kirk's right-hand-man.
Yes, this is correct. Kirk is going to be the main architect. I have
been heavily involved and will continue to be.
:> >> The use of the "vfs_default" to make unimplemented VOP's
:
:> I beg to differ. The only difference is that we pass through
:> multiple layers before we hit the bottom of the stack. There is
:...
:Well I believe that Kirk considers them misguided too, but he stated that
:he wasn't going to remove them without serious thought about the alternatives.
The vfs op callout layering has not been on the radar screen. There
are much too many other more serious problems. I really doubt that any
changes will be made to this piece any time in the next year or even two,
if at all.
The main items on the radar screen are related to buffer management
(struct buf stuff. For example, preventing VM blockages due to pages
being wired by write I/O's), VFS locking and reference count issues
(for example, namei lookups, blockages in the pager and syncer due to
vnode locks held by blocked processes, etc...), and interactions
between VFS and VM (for example: moving away from VOP_READ/VOP_WRITE
and moving more towards a getpages/putpages model).
None of the items have been set in stone yet. We're waiting for Kirk
to get back from vacation and get back into the groove.
-Matt
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