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From: John Baldwin <jhb@freebsd.org>
To: Konstantin Belousov <kib@freebsd.org>
Subject: Re: svn commit: r241556 - in head/sys: kern sys
Date: Mon, 15 Oct 2012 08:37:04 -0400
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On Sunday, October 14, 2012 3:43:37 pm Konstantin Belousov wrote:
> Author: kib
> Date: Sun Oct 14 19:43:37 2012
> New Revision: 241556
> URL: http://svn.freebsd.org/changeset/base/241556
> 
> Log:
>   Add a KPI to allow to reserve some amount of space in the numvnodes
>   counter, without actually allocating the vnodes. The supposed use of
>   the getnewvnode_reserve(9) is to reclaim enough free vnodes while the
>   code still does not hold any resources that might be needed during the
>   reclamation, and to consume the slack later for getnewvnode() calls
>   made from the innards. After the critical block is finished, the
>   caller shall free any reserve left, by getnewvnode_drop_reserve(9).

Can you describe an intended use-case for this?

-- 
John Baldwin