Re: Interaction between Xen and XFS: stray RW mappings

David Chinner
2007-10-15T04:26:18Z

On Sun, Oct 14, 2007 at 09:18:17PM -0700, Jeremy Fitzhardinge wrote:
> David Chinner wrote:
> > With defaults - little effect as vmap should never be used. It's
> > only when you start using larger block sizes for metadata that this
> > becomes an issue. The CONFIG_XEN workaround should be fine until we
> > get a proper vmap cache....
>
> 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.

Cheers,

Dave.
--
Dave Chinner
Principal Engineer
SGI Australian Software Group