Re: Interaction between Xen and XFS: stray RW mappings

dean gaudet
2007-10-22T04:28:41Z

On Sun, 21 Oct 2007, Jeremy Fitzhardinge wrote:

> dean gaudet wrote:
> > On Mon, 15 Oct 2007, Nick Piggin wrote:
> >
> >
> >> Yes, as Dave said, vmap (more specifically: vunmap) is very expensive
> >> because it generally has to invalidate TLBs on all CPUs.
> >>
> >
> > why is that? ignoring 32-bit archs we have heaps of address space
> > available... couldn't the kernel just burn address space and delay global
> > TLB invalidate by some relatively long time (say 1 second)?
> >
>
> Yes, that's precisely the problem. xfs does delay the unmap, leaving
> stray mappings, which upsets Xen.

sounds like a bug in xen to me :)

-dean