Re: [PATCH part2 v2 0/8] Arrange hotpluggable memory as ZONE_MOVABLE

From: H. Peter Anvin
Date: Mon Oct 14 2013 - 16:43:26 EST


On 10/14/2013 01:37 PM, Yinghai Lu wrote:
>>
>> Optimizing NUMA boot just requires moving the heavy lifting to
>> appropriate NUMA nodes. It doesn't require that early boot phase
>> should strictly follow NUMA node boundaries.
>
> At end of day, I like to see all numa system (ram/cpu/pci) could have
> non boot nodes to be hot-removed logically. with any boot command
> line.
>

I don't think that is realistic without hardware support, simply because
all it takes is a single page of kernel locked memory to prevent a page
from being removed. The only realistic way around that, I believe, is
to remove the identity-mapping in the kernel, but it still has all kinds
of funnies involving devices and DMA.

-hpa

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