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[Xen-devel] TSC virtualization across different host frequency platform

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Subject: [Xen-devel] TSC virtualization across different host frequency platform migration
From: "Dong, Eddie" <eddie.dong@xxxxxxxxx>
Date: Wed, 22 Apr 2009 09:32:43 +0800
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Cc: "Tian, Kevin" <kevin.tian@xxxxxxxxx>, "Dong, Eddie" <eddie.dong@xxxxxxxxx>, Keir Fraser <keir.fraser@xxxxxxxxxxxxx>, "Zhang, Xiantao" <xiantao.zhang@xxxxxxxxx>
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Thread-topic: TSC virtualization across different host frequency platform migration
Keir and all:
        Recently we are considering the potential issue of TSC virtualization 
across different frequency platform migration. Current approach will lead to 
synchronization issue between guest TSC and wall clock. Software trap and 
emulate can solve the problem with the payment of performance overhead which is 
not optimal. We want to propose smart scaling algorithm which can continuously 
use HW TSC_OFFSET and maintain long time synchronization of guest TSC.  The 
details are in attached document. Can you have a look and provide comments?
        Thanks. BTW of course PV time is another solution which is not covered 
in this proposal.


Attachment: tsc-scale2.pdf
Description: tsc-scale2.pdf

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