Date: Wed, 4 May 2005 21:27:21 -0400 (EDT)
From: Rik van Riel <riel@redhat.com>
To: William Jordan <bjordan.ics@gmail.com>
cc: Andy Isaacson <adi@hexapodia.org>,
       Caitlin Bestler <caitlin.bestler@gmail.com>,
       Andrew Morton <akpm@osdl.org>, linux-kernel@vger.kernel.org,
       openib-general@openib.org, hch@infradead.org,
       Timur Tabi <timur.tabi@ammasso.com>
Subject: Re: [openib-general] Re: [PATCH][RFC][0/4] InfiniBand userspace
 verbs implementation
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Message-ID: <Pine.LNX.4.61.0505042123410.18390@chimarrao.boston.redhat.com>
References: <469958e00504291731eb8287c@mail.gmail.com>  <20050503184325.GA19351@hexapodia.org>
 <78d18e2050504112240e43a08@mail.gmail.com>
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On Wed, 4 May 2005, William Jordan wrote:
> On 5/3/05, Andy Isaacson <adi@hexapodia.org> wrote:
> > Rather than replacing the fully-registered pages with pages of zeros,
> > you could simply unmap them.
> 
> I don't like this option. It is nearly free to map all of the pages to
> the zero-page. You never have to allocate a page if the user never
> writes to it.

Unmapping should work fine, as long as the VMA flags are
set appropriately.  The page fault handler can take care
of the rest...

-- 
"Debugging is twice as hard as writing the code in the first place.
Therefore, if you write the code as cleverly as possible, you are,
by definition, not smart enough to debug it." - Brian W. Kernighan
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