Re: [RFC 0/3] Implementation of cgroup isolation

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Mon, 28 Mar 2011 11:01:18 -0700
Ying Han <yinghan@google.com> wrote:

> On Mon, Mar 28, 2011 at 2:39 AM, Michal Hocko <mhocko@suse.cz> wrote:
> > Hi all,
> >
> > Memory cgroups can be currently used to throttle memory usage of a group of
> > processes. It, however, cannot be used for an isolation of processes from
> > the rest of the system because all the pages that belong to the group are
> > also placed on the global LRU lists and so they are eligible for the global
> > memory reclaim.
> >
> > This patchset aims at providing an opt-in memory cgroup isolation. This
> > means that a cgroup can be configured to be isolated from the rest of the
> > system by means of cgroup virtual filesystem (/dev/memctl/group/memory.isolated).
> 
> Thank you Hugh pointing me to the thread. We are working on similar
> problem in memcg currently
> 
> Here is the problem we see:
> 1. In memcg, a page is both on per-memcg-per-zone lru and global-lru.
> 2. Global memory reclaim will throw page away regardless of cgroup.
> 3. The zone->lru_lock is shared between per-memcg-per-zone lru and global-lru.
> 
> And we know:
> 1. We shouldn't do global reclaim since it breaks memory isolation.
> 2. There is no need for a page to be on both LRU list, especially
> after having per-memcg background reclaim.
> 
> So our approach is to take off page from global lru after it is
> charged to a memcg. Only pages allocated at root cgroup remains in
> global LRU, and each memcg reclaims pages on its isolated LRU.
> 

Why you don't use cpuset and virtual nodes ? It's what you want.

Thanks,
-Kame

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