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RE: [Xen-devel] Re: [PATCH 1/4] CPU online/offline support in Xen

To: "Haitao Shan" <maillists.shan@xxxxxxxxx>, "Keir Fraser" <keir.fraser@xxxxxxxxxxxxx>
Subject: RE: [Xen-devel] Re: [PATCH 1/4] CPU online/offline support in Xen
From: "Shan, Haitao" <haitao.shan@xxxxxxxxx>
Date: Thu, 11 Sep 2008 16:02:58 +0800
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Thread-topic: [Xen-devel] Re: [PATCH 1/4] CPU online/offline support in Xen
Hi, Keir,

Attached is the updated patch using the methods as you described in
another mail.
What do you think of the one?

Signed-off-by:  Shan Haitao <haitao.shan@xxxxxxxxx> 

Best Regards
Haitao Shan

Haitao Shan wrote:
> Agree. Placing migration in stop_machine context will definitely make
> our jobs easier. I will start making a new patch tomorrow. :)
> I place the migraton code outside the stop_machine_run context, partly
> because I am not quite sure how long it will take to migrate all the
> vcpus away. If it takes too much time, all useful works are blocked
> since all cpus are in the stop_machine context. Of course, I borrowed
> the ideas from kernel, which also let me made the desicion.
> 2008/9/10 Keir Fraser <keir.fraser@xxxxxxxxxxxxx>:
>> I feel this is more complicated than it needs to be.
>> How about clearing VCPUs from the offlined CPU's runqueue from the
>> very end of __cpu_disable()? At that point all other CPUs are safely
>> in softirq context with IRQs disabled, and we are running on the
>> correct CPU (being offlined). We could have a hook into the
>> scheduler subsystem at that point to break affinities, assign to
>> different runqueues, etc. We would just need to be careful not to
>> try an IPI. :-) This approach would not need a cpu_schedule_map
>> (which is really increasing code fragility imo, by creating possible
>> extra confusion about which cpumask is the wright one to use in a
>> given situation).  
>> My feeling, unless I've missed something, is that this would make
>> the patch quite a bit smaller and with a smaller spread of code
>> changes. 
>>  -- Keir
>> On 9/9/08 09:59, "Shan, Haitao" <haitao.shan@xxxxxxxxx> wrote:
>>> This patch implements cpu offline feature.
>>> Best Regards
>>> Haitao Shan
>> _______________________________________________
>> Xen-devel mailing list
>> Xen-devel@xxxxxxxxxxxxxxxxxxx
>> http://lists.xensource.com/xen-devel

Attachment: cpu_offline.patch
Description: cpu_offline.patch

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