Re: [PATCH RFC 0/3] mm: Reduce IO by improving algorithm of memcg pagecache pages eviction

From: Michal Hocko
Date: Thu Jan 10 2019 - 04:57:56 EST


On Thu 10-01-19 12:42:02, Kirill Tkhai wrote:
[...]
> In general, I think a some time useful design is not a Bible, that nobody
> is allowed to change. We should not limit us in something, in case of this
> has a sense and may be useful. This is just a note in general.

But any semantic exported to the userspace and real application
depending on it is carved in stone for ever. And this is the case here I
am afraid. So if we really need some sort of soft unmapping or
reparenting a memory from a memcg then we really need to find a
different way. I do not see a straightforward way right now TBH.
--
Michal Hocko
SUSE Labs