Re: [RFC PATCH] mm: memcontrol: memory+swap accounting for cgroup-v2

From: Tejun Heo
Date: Tue Dec 19 2017 - 12:34:04 EST


On Tue, Dec 19, 2017 at 09:23:29AM -0800, Shakeel Butt wrote:
> To provide consistent memory usage history using the current
> cgroup-v2's 'swap' interface, an additional metric expressing the
> intersection of memory and swap has to be exposed. Basically memsw is
> the union of memory and swap. So, if that additional metric can be

Exposing anonymous pages with swap backing sounds pretty trivial.

> used to find the union. However for consistent memory limit
> enforcement, I don't think there is an easy way to use current 'swap'
> interface.

Can you please go into details on why this is important? I get that
you can't do it as easily w/o memsw but I don't understand why this is
a critical feature. Why is that?