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Date:      Tue, 27 Aug 1996 12:35:14 +0900 (JST)
From:      Michael Hancock <michaelh@cet.co.jp>
To:        Terry Lambert <terry@lambert.org>
Cc:        eric@ms.uky.edu, freebsd-fs@FreeBSD.ORG, current@FreeBSD.ORG
Subject:   Re: vclean (was The VIVA file system)
Message-ID:  <Pine.SV4.3.93.960827115155.17910A-100000@parkplace.cet.co.jp>
In-Reply-To: <199608270220.TAA23773@phaeton.artisoft.com>

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On Mon, 26 Aug 1996, Terry Lambert wrote:

> > I think what needs to be looked at is having more synchronized buffer
> > cache/vnode recycling policies.
> 
> Inode data, disklabel data, and any other FS object which is not file
> contents is not cached under the current policy.

The vnode/inode association with a vnhash() you mentioned before makes
sense.  I wonder how hard it would be to manage the buffer
cache/vnodes/inodes with more synergy (sorry I couldn't think of a better
word).

> Further, dissociating buffers from vnodes does not require that they
> be returned to a global pool for clean-behind.

There's an in-place free list that can have valid buffers hanging off of
them and vnodes go on the list when inactive() is called.  I guess the
freelist should be called the inactive list.

getnewvnode()
	vgone()
		vclean() should only be called when it needs to, such as when
file activity moves to a different fs and there aren't enough vnodes.

The vnode pool was a fixed size pool in lite, but someone put in a
malloc() into getnewvnode().  The vnode pool is kind of wired so I think
it can now grow, but it can't shrink unless there's some free()s being
done somewhere where I haven't noticed.

> I think the non-opacity of vnodes is a mistake.

I guess they didn't have time to get this aspect right.

Some of the semantics are very interesting though, they look very
different from the SysV vnodes I read about in the Vahalia book. 


Regards,


Mike Hancock





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