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Date: Fri, 2 May 1997 13:14:47 +0100 (BST)
From: Doug Rabson <dfr@nlsystems.com>
To: Poul-Henning Kamp <phk@dk.tfs.com>
cc: current@freebsd.org
Subject: Re: vnode->v_usage 
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On Fri, 2 May 1997, Poul-Henning Kamp wrote:

> 
> >I don't have any performance numbers but it seems to work fine.  I think
> >the cache should just call vtouch for all vnodes and not check the usage
> >count.
> OK.
> 
> >Also vtouch should take the v_interlock simple_lock before reading
> >the v_usecount field as specified by vnode.h.
> 
> Ok, now I'm in doubt here...  Which of these two places are the
> correct place to release the interlock, I've marked the candidates
> with XXX, I pressume the later, right ?

I think that you don't need the v_interlock for using v_freelist so
probably releasing it earlier is better.  Maybe something like:

	int usecount;
	simple_lock(&vp->v_interlock);
	usecount = vp->v_usecount;
	simple_unlock(&vp->v_interlock);
	if (usecount)
		...
	...


--
Doug Rabson				Mail:  dfr@nlsystems.com
Nonlinear Systems Ltd.			Phone: +44 181 951 1891