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Re: [XEN RFC PATCH 26/40] xen/arm: Add boot and secondary CPU to NUMA system

  • To: Wei Chen <Wei.Chen@xxxxxxx>
  • From: Jan Beulich <jbeulich@xxxxxxxx>
  • Date: Thu, 26 Aug 2021 14:26:08 +0200
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  • Cc: Bertrand Marquis <Bertrand.Marquis@xxxxxxx>, "xen-devel@xxxxxxxxxxxxxxxxxxxx" <xen-devel@xxxxxxxxxxxxxxxxxxxx>, "sstabellini@xxxxxxxxxx" <sstabellini@xxxxxxxxxx>, Julien Grall <julien@xxxxxxx>
  • Delivery-date: Thu, 26 Aug 2021 12:26:23 +0000
  • List-id: Xen developer discussion <xen-devel.lists.xenproject.org>

On 26.08.2021 14:08, Wei Chen wrote:
>> From: Jan Beulich <jbeulich@xxxxxxxx>
>> Sent: 2021年8月26日 17:40
>> On 26.08.2021 10:49, Julien Grall wrote:
>>> Right, but again, why do you want to solve the problem on Arm and not
>>> x86? After all, NUMA is not architecture specific (in fact you move most
>>> of the code in common).
> I am not very familiar with x86, so when I was composing this patch series,
> I always thought that if I could solve it inside Arm Arch, I would solve it
> inside Arm Arch. That seems a bit conservative, and inappropriate on solving
> this problem.
>>> In fact, the risk, is someone may read arch/x86 and doesn't realize the
>>> CPU is not in the node until late on Arm.
>>> So I think we should call numa_add_cpu() around the same place on all
>>> the architectures.
>> FWIW: +1
> I agree. As Jan in this discussion. How about following current x86's
> numa_add_cpu behaviors in __start_xen, but add some code to revert
> numa_add_cpu when cpu_up failed (both Arm and x86)?

Sure - if we don't clean up properly on x86 on a failure path, I'm all
for having that fixed.




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