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SubjectRe: [PATCH] xen: avoid hypercalls when updating unpinned pud/pmd

* Jeremy Fitzhardinge <jeremy@goop.org> wrote:

> When operating on an unpinned pagetable (ie, one under construction or
> destruction), it isn't necessary to use a hypercall to update a
> pud/pmd entry. Jan Beulich observed that a similar optimisation
> avoided many thousands of hypercalls while doing a kernel build.
>
> One tricky part is that early in the kernel boot there's no page
> structure, so we can't check to see if the page is pinned. In that
> case, we just always use the hypercall.
>
> Signed-off-by: Jeremy Fitzhardinge <jeremy.fitzhardinge@citrix.com>
> Cc: Jan Beulich <jbeulich@novell.com>

applied to tip/x86/xen, thanks Jeremy.

Ingo


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