From: Christoph Lameter <cl@linux.com>
To: Mordae <mordae@anilinux.org>
Cc: linux-mm@kvack.org
Subject: Re: COW userspace memory mapping question
Date: Fri, 11 Mar 2011 09:15:42 -0600 (CST) [thread overview]
Message-ID: <alpine.DEB.2.00.1103110914290.18585@router.home> (raw)
In-Reply-To: <474da85b78a7bd1e16726b72e9162f5c@anilinux.org>
On Thu, 10 Mar 2011, Mordae wrote:
> On Thu, 10 Mar 2011 15:33:31 -0600 (CST), Christoph Lameter <cl@linux.com>
> wrote:
> > First establish an RW mapping of the file.
> > Then -- when you want to take the snapshot -- unmap it and do two mmaps
> to
> > the old and new location. Make both readonly and MAP_PRIVATE. That will
> > cause the kernel to create readonly pages that are subject to COW.
>
> I see, that seems reasonable. But what if I was picky and want to snapshot
> that piece of memory continuously? Let's say once in several minutes, then
> let some thread to do stuffs to the original using consistent information
> from the snapshot.
Keep the RW mapping around and tear down and repeat the MAP_PRIVATE mmaps
areas as needed? Updates would have to be done to the RW mapping.
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next prev parent reply other threads:[~2011-03-11 15:15 UTC|newest]
Thread overview: 7+ messages / expand[flat|nested] mbox.gz Atom feed top
2011-03-08 21:38 Mordae
2011-03-10 19:13 ` Christoph Lameter
2011-03-10 21:00 ` Mordae
2011-03-10 21:33 ` Christoph Lameter
2011-03-10 22:11 ` Mordae
2011-03-11 15:15 ` Christoph Lameter [this message]
2011-03-11 16:33 ` Jan Dvorak
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