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RE: [Xen-devel] RE: [Patch] Fix IDLE issue with sedf scheduler on IA64

To: "Magenheimer, Dan \(HP Labs Fort Collins\)" <dan.magenheimer@xxxxxx>
Subject: RE: [Xen-devel] RE: [Patch] Fix IDLE issue with sedf scheduler on IA64
From: "Tian, Kevin" <kevin.tian@xxxxxxxxx>
Date: Wed, 13 Jul 2005 21:34:13 +0800
Cc: xen-devel@xxxxxxxxxxxxxxxxxxx, xen-ia64-devel@xxxxxxxxxxxxxxxxxxx
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Thread-topic: [Xen-devel] RE: [Patch] Fix IDLE issue with sedf scheduler on IA64
>From: xen-devel-bounces@xxxxxxxxxxxxxxxxxxx
>[mailto:xen-devel-bounces@xxxxxxxxxxxxxxxxxxx] On Behalf Of
>Dan (HP Labs Fort Collins)
>Sent: Wednesday, July 13, 2005 8:25 PM
>To: Tian, Kevin
>Is there a better way (for ia64)?  I kind of like the solution
>Keir and Ian imply... is it possible in context_switch to simply
>"refuse" to switch to the idle domain?   E.g. if the idle domain
>is the target of the switch, instead switch to domain0 (and
>make it runnable)?

This seems not easy to be simply done in context_switch without common
change. Preventing switch to IDLE is easy, and a simple check in
context_switch can achieve. However the really bad thing is about
housekeep info within scheduler. Eg. domain0 may have been placed on
waitq, with begin of next period still far away. Stealing slice of IDLE
to Dom0 without notifying scheduler, may mess the future decision since
next schedule will happen on Dom0's context and base on dom0's statistic


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