Re: [Xen-devel] [PATCH RFC] mm/memory_hotplug: Introduce memory block types

[David Hildenbrand <david@xxxxxxxxxx>]

On 04/10/2018 17:28, Michal Suchánek wrote:
> On Thu, 4 Oct 2018 10:13:48 +0200
> David Hildenbrand <david@xxxxxxxxxx> wrote:
> 
> ok, so what is the problem here?
> 
> Handling the hotplug in userspace through udev may be suboptimal and
> kernel handling might be faster but that's orthogonal to the problem at
> hand.

Yes, that one to solve is a different story.

> 
> The state of the art is to determine what to do with hotplugged memory
> in userspace based on platform and virtualization type.

Exactly.

> 
> Changing the default to depend on the driver that added the memory
> rather than platform type should solve the issue of VMs growing
> different types of memory device emulation.

Yes, my original proposal (this patch) was to handle it in the kernel
for known types. But as we learned, there might be some use cases that
might still require to make a decision in user space.

So providing the user space either with some type hint (auto-online vs.
standby) or the driver that added it (system vs. hyper-v ...) would
solve the issue.

> 
> Am I missing something?
> 

No, that's it. Thanks!

> Thanks
> 
> Michal
> 


-- 

Thanks,

David / dhildenb

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