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[Xen-devel] [PATCH 0/3] x86: adjust entry frame generation

  • To: "xen-devel" <xen-devel@xxxxxxxxxxxxx>
  • From: "Jan Beulich" <JBeulich@xxxxxxxx>
  • Date: Tue, 02 Oct 2012 16:20:40 +0100
  • Delivery-date: Tue, 02 Oct 2012 15:20:57 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xen.org>

This set of patches converts the way frames gets created from
using PUSHes/POPs to using MOVes, thus allowing (in certain
cases) to avoid saving/restoring part of the register set.

While the place where the (small) win from this comes from varies
between CPUs, the net effect is a 1 to 2% reduction on a
combined interruption entry and exit when the full state save
can be avoided.

1: use MOV instead of PUSH/POP when saving/restoring register state
2: consolidate frame state manipulation functions
3: save only partial register state where possible

Signed-off-by: Jan Beulich <jbeulich@xxxxxxxx>

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