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[Xen-devel][PATCH] unshadow the page table page which are used as data p

To: <xen-devel@xxxxxxxxxxxxxxxxxxx>
Subject: [Xen-devel][PATCH] unshadow the page table page which are used as data page
From: "Xin, Xiaohui" <xiaohui.xin@xxxxxxxxx>
Date: Wed, 5 Dec 2007 10:48:20 +0800
Cc: "Kay, Allen M" <allen.m.kay@xxxxxxxxx>, Tim.Deegan@xxxxxxxxxx
Delivery-date: Tue, 04 Dec 2007 18:51:44 -0800
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Thread-index: Acg26Uvueut2y0FASzqSCpiH31X1Jw==
Thread-topic: [Xen-devel][PATCH] unshadow the page table page which are used as data page

The patch deals with the situation which guest OS uses unused page table pages as data pages and write data to them. The pages will still be grabbed by Xen as page table pages, and lots of unnecessary page faults occur.

The patch will check if the data guest writes to the page table contains valid mfn or not, if not, we believe it is a data page now and then unshadow the page.

The patch improves the VT-D NIC performance a lot.

 

Signed-off-by: Xin Xiaohui <xiaohui.xin@xxxxxxxxx>

     

Attachment: perf2.diff
Description: perf2.diff

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