From owner-freebsd-hackers  Mon Apr 16 23: 2:44 2001
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To: Julian Elischer <julian@elischer.org>
Subject: Re: vm balance 
Cc: Rik van Riel <riel@conectiva.com.br>,
	freebsd-hackers@FreeBSD.ORG,
	Matt Dillon <dillon@earth.backplane.com>, David Xu <bsddiy@21cn.com>
In-Reply-To: Your message of "Tue, 10 Apr 2001 22:14:28 PDT."
             <3AD3E834.AFB6C5BA@elischer.org> 
Date: Mon, 16 Apr 2001 23:02:19 -0700
From: Kirk McKusick <mckusick@mckusick.com>
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    Date: Tue, 10 Apr 2001 22:14:28 -0700
    From: Julian Elischer <julian@elischer.org>
    To: Rik van Riel <riel@conectiva.com.br>
    CC: Matt Dillon <dillon@earth.backplane.com>, David Xu <bsddiy@21cn.com>,
       freebsd-hackers@FreeBSD.ORG, mckusick@mckusick.com
    Subject: Re: vm balance

    Rik van Riel wrote:

    > 
    > I'm curious about the other things though ... FreeBSD still seems
    > to have the early 90's abstraction layer from Mach and the vnode
    > cache doesn't seem to grow and shrink dynamically (which can be a
    > big win for systems with lots of metadata activity).
    > 
    > So while it's true that FreeBSD's VM balancing seems to be the
    > best one out there, I'm not quite sure about the rest of the VM...
    > 

    Many years ago Kirk was talking about merging the vm objects
    and the vnodes..  (they tend to come in pairs anyhow)

    I still think it might be an idea worth investigating further.

    kirk?

    -- 
	  __--_|\  Julian Elischer
	 /       \ julian@elischer.org
	(   OZ    ) World tour 2000-2001
    ---> X_.---._/  
		v

I am still of the opinion that merging VM objects and vnodes would
be a good idea. Although it would touch a huge number of lines of
code, when the dust settled, it would simplify some nasty bits of
the system. This merger is really independent of making the number
of vnodes dynamic. Under the old name cache implementation, decreasing
the number of vnodes was slow and hard. With the current name cache
implementation, decreasing the number of vnodes would be easy. I
concur that adding a dynamically sized vnode cache would help
performance on some workloads.

	Kirk McKusick

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