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SubjectRe: [PATCH 3/3] acpi, memory-hotplug: Support getting hotplug info from SRAT.
On 01/26/2013 09:29 AM, H. Peter Anvin wrote:
> On 01/25/2013 05:12 PM, Andrew Morton wrote:
>> On Fri, 25 Jan 2013 17:42:09 +0800
>> Tang Chen<tangchen@cn.fujitsu.com> wrote:
>>
>>> NOTE: Using this way will cause NUMA performance down because the whole node
>>> will be set as ZONE_MOVABLE, and kernel cannot use memory on it.
>>> If users don't want to lose NUMA performance, just don't use it.
>>
>> I agree with this, but it means that nobody will test any of your new code.
>>
>> To get improved testing coverage, can you think of any temporary
>> testing-only patch which will cause testers to exercise the
>> memory-hotplug changes?
>>
>
> There is another problem: if ALL the nodes in the system support
> hotpluggable memory, what happens?
>

Hi HPA,

I think I missed this case. If all the memory is hotpluggable, and user
specified
movablemem_map=acpi, all the memory could be set as movable, and the
kernel will
fail to start.

I will post a patch to fix it. How about always keep node0 unhotpluggable ?

Thanks. :)


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