Re: [PATCH 4 of 4] Support new xl command cpupool-numa-split

[Juergen Gross <juergen.gross@ts.fujitsu.com>]

On 12/08/10 15:12, Ian Campbell wrote:
> On Wed, 2010-12-08 at 13:41 +0000, Juergen Gross wrote:
>> On 12/08/10 14:38, Ian Campbell wrote:
>>> On Wed, 2010-12-08 at 13:17 +0000, Juergen Gross wrote:
>>>> On 12/08/10 14:12, Ian Campbell wrote:
>>>>> On Wed, 2010-12-08 at 12:20 +0000, Juergen Gross wrote:
>>>>>> On 12/08/10 12:16, Ian Campbell wrote:
>>>>>>> Can this loop be merged with the preceding loop, with the body being the
>>>>>>> else case of the if?
>>>>>>
>>>>>> No. I have to add new cpus first to avoid a cpupool without cpus in between.
>>>>>
>>>>> ok.
>>>>>
>>>>> I was thinking that because this function only gets here if there is a
>>>>> single pool that all CPUs must be in that pool -- but that's not
>>>>> actually true is it? Even if that were the common case there's nothing
>>>>> to enforce that.
>>>>
>>>> Perhaps I should add a comment to avoid a problem later...
>>>
>>> That would certainly help.
>>>
>>> The alternative would be to bail out if all cpus are not associated with
>>> Pool-0, not just when there are>   1 pools. That would be consistent with
>>> the function only acting on the default configuration.
>>
>> I suspect NUMA systems are subject to cpu hot plug...
>
> And hotplugged CPUs don't automatically go into Pool-0?

I just checked it: they ARE added to Pool-0.

This rises another problem: it would be nice to adjust the NUMA
splitting after a hot-plug of a cpu...
An "update" option to xl cpupool-numa-split would be appropriate,
I think. It should move cpus from Pool 0 to the correct node pools
and create new node pools if necessary.

I'll prepare another patch later...


Juergen

-- 
Juergen Gross                 Principal Developer Operating Systems
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