Re: [PATCH v2 5/5] mm, memory_hotplug: Refactor shrink_zone/pgdat_span

[David Hildenbrand <david@redhat.com>]

On 28.11.18 08:07, Oscar Salvador wrote:
> On Wed, 2018-11-28 at 07:50 +0100, Michal Hocko wrote:
>>
>> I didn't get to read through this whole series but one thing that is
>> on
>> my todo list for a long time is to remove all this stuff. I do not
>> think
>> we really want to simplify it when there shouldn't be any real reason
>> to
>> have it around at all. Why do we need to shrink zone/node at all?
>>
>> Now that we can override and assign memory to both normal na movable
>> zones I think we should be good to remove shrinking.
> 
> I feel like I am missing a piece of obvious information here.
> Right now, we shrink zone/node to decrease spanned pages.
> I thought this was done for consistency, and in case of the node, in
> try_offline_node we use the spanned pages to go through all sections
> to check whether the node can be removed or not.
> 

I am also not sure if that can be done. Anyhow, simplifying first and
getting rid later is in my opinion also good enough. One step at a time :)

> From your comment, I understand that we do not really care about
> spanned pages. Why?
> Could you please expand on that?
> 
> And if we remove it, would not this give to a user "bad"/confusing
> information when looking at /proc/zoneinfo?
> 
> 
> Thanks
> 


-- 

Thanks,

David / dhildenb