[Xen-ia64-devel][PATCH]Let XEN handle identity mapping for xenolinux region 7

["Xu, Anthony" <anthony.xu@xxxxxxxxx>]

Let XEN handle identity mapping for xenolinux region 7

I noticed that in the process of KB on dom0,  half of slow reflection is
ALT_DTLB_MISS,
See below data,  ARR16 is ALT_DTLB_MISS.


(XEN) slow reflection                   TOTAL[  22904618]
(XEN)                    ARR00[   4635847]  ARR01[         0]  ARR02[
0]
  ARR03[         0]
(XEN)                    ARR04[   2010044]  ARR05[         0]  ARR06[
0]
  ARR07[         0]
(XEN)                    ARR08[   3908798]  ARR09[         0]  ARR10[
0]
  ARR11[         0]
(XEN)                    ARR12[         0]  ARR13[         0]  ARR14[
0]
  ARR15[         0]
(XEN)                    ARR16[  11575236]

As we known, region 7 on xenolinux is identity mapping.
So XEN can handle this kind of ALT_DTLB_MISS for xenolinux.

Applying this patch, most of ALT_DTLB_MISS slow reflection disappeared.
I get below perfomance data by runing KB on dom0.

without patch           with patch                      improvement
real    17m6.188s               real    16m41.390s      2.44%
user    15m49.760s      user    15m49.140s      almost same
sys     1m2.790s                sys     0m53.570s               14.68%



--Anthony

Attachment: handle_alttlb.patch
Description: handle_alttlb.patch

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