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[xfs-masters] Re: Interaction between Xen and XFS: stray RW mappings

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Subject: [xfs-masters] Re: Interaction between Xen and XFS: stray RW mappings
From: Christoph Hellwig <hch@xxxxxx>
Date: Mon, 15 Oct 2007 10:31:41 +0200
Cc: Jeremy Fitzhardinge <jeremy@xxxxxxxx>, David Chinner <dgc@xxxxxxx>, Nick Piggin <nickpiggin@xxxxxxxxxxxx>, xfs@xxxxxxxxxxx, Xen-devel <xen-devel@xxxxxxxxxxxxxxxxxxx>, Linux Kernel Mailing List <linux-kernel@xxxxxxxxxxxxxxx>, Mark Williamson <mark.williamson@xxxxxxxxxxxx>, Morten B?geskov <xen-users@xxxxxxxxxxxxxxxxxx>
In-reply-to: <20071015042546.GI995458@sgi.com>
References: <470FA7C3.90404@goop.org> <200710151415.07248.nickpiggin@yahoo.com.au> <4712BB05.1020701@goop.org> <200710151726.08387.nickpiggin@yahoo.com.au> <4712E1AA.501@goop.org> <20071015041133.GH995458@sgi.com> <4712EA09.6000102@goop.org> <20071015042546.GI995458@sgi.com>
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On Mon, Oct 15, 2007 at 02:25:46PM +1000, David Chinner wrote:
> > Hm, well I saw the problem with a filesystem made with mkfs.xfs with no
> > options, so there must be at least *some* vmapping going on there.
> 
> Sorry - I should have been more precise - vmap should never be used in
> performance critical paths on default configs.  Log recovery will
> trigger vmap/vunmap usage, so this is probably what you are seeing.

The iclogs are also vmapped, but they aren't unmapped until unmount so
this optimizations doesn't matter either.


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