Re: [PATCH 0/4] Support dynamic (de)configuration of memory

David Hildenbrand
2025-10-08T09:43:11Z

On 08.10.25 11:12, Heiko Carstens wrote:
> On Wed, Oct 08, 2025 at 10:02:26AM +0200, David Hildenbrand wrote:
>> On 08.10.25 08:05, Sumanth Korikkar wrote:
>>>>> chmem changes would look like:
>>>>> chmem -c 128M -m 1 : configure memory with memmap-on-memory enabled
>>>>> chmem -g 128M : deconfigure memory
>>>>
>>>> I wonder if the above two are really required. I would expect most/all users
>>>> to simply keep using -e / -d.
>>>>
>>>> Sure, there might be some corner cases, but I would assume most people to
>>>> not want to care about memmap-on-memory with the new model.
>
> ...
>
>>> 2) If the administrator forgets to configure
>>> memory_hotplug.memmap_on_memory=Y, the following steps can be taken:
>>> Rescue from OOM situations: configure with memmap-on-memory enabled, online it.
>>
>> That's my point: I don't consider either very likely to be used by actual
>> admins.
>
> But does it really hurt to add those options?

Oh, I don't think so.

I was just a bit surprised to see it in the first version of this,
because it felt to me like this is something to be added later on top
quite easily/cleanly.

In particular, patch #2 would get a lot lighter also in terms of
documentation.

So no strong opinion about adding it, but maybe we can just split it
into a separate patch and focus on patch #2 on the real magic?

--
Cheers

David / dhildenb