From: Jeremy Fitzhardinge Date: Sat, 31 May 2008 00:24:27 +0000 (+0100) Subject: xen: avoid hypercalls when updating unpinned pud/pmd X-Git-Tag: v2.6.27-rc1~1106^2~251^24~12 X-Git-Url: http://git.openpandora.org/cgi-bin/gitweb.cgi?a=commitdiff_plain;h=e2426cf85f8db5891fb5831323d2d0c176c4dadc;p=pandora-kernel.git xen: avoid hypercalls when updating unpinned pud/pmd 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 Cc: Jan Beulich Signed-off-by: Ingo Molnar --- Reading git-diff-tree failed