Re: [PATCH] mm: add memory.compact_unevictable_allowed cgroup attribute

[Michal Hocko]

On Wed 18-03-26 12:55:49, Shakeel Butt wrote:
[...]
> IMO we should actually deprecate compact_unevictable_allowed and always allow
> compaction for unevictable memory. We should decouple the notion of mlocked
> memory from the pinned/unmovable memory. Pinned memory has much more
> consequences on the system related to fragmentation and availability of larger
> folios than mlocked memory. If there are applications which need unmovable
> memory, they should request it explicitly. I don't think there is an API for
> such memory but for such use-cases, it makes sense to have an explicit API.

That would be really hard to do in a backward compatible way and there
are workloads (e.g. RT) where mlock is supposed to imply even no minor
faults.
-- 
Michal Hocko
SUSE Labs