On Wed 11-06-14 08:31:09, Tejun Heo wrote: > Hello, Michal. > > On Wed, Jun 11, 2014 at 09:57:29AM +0200, Michal Hocko wrote: > > Is this the kind of symmetry Tejun is asking for and that would make > > change is Nack position? I am still not sure it satisfies his soft > > Yes, pretty much. What primarily bothered me was the soft/hard > guarantees being chosen by a toggle switch while the soft/hard limits > can be configured separately and combined. The last consensus at LSF was that there would be a knob which will distinguish hard/best effort behavior. The weaker semantic has strong usecases IMHO so I wanted to start with it and add a knob for the hard guarantee later when explicitly asked for. Going with min, low, high and hard makes more sense to me of course. > > guarantee objections from other email. > > I was wondering about the usefulness of "low" itself in isolation and I think it has more usecases than "min" from simply practical POV. OOM means a potential service down time and that is a no go. Optimistic isolation on the other hand adds an advantages of the isolation most of the time while not getting completely flat on an exception (be it misconfiguration or a corner case like mentioned during the discussion). That doesn't mean "min" is not useful. It definitely is, the category of usecases will be more specific though. > I still think it'd be less useful than "high", but as there seem to be > use cases which can be served with that and especially as a part of a > consistent control scheme, I have no objection. > > "low" definitely requires a notification mechanism tho. Would vmpressure notification be sufficient? That one is in place for any memcg which is reclaimed. Or are you thinking about something more like oom_control? -- Michal Hocko SUSE Labs -- To unsubscribe, send a message with 'unsubscribe linux-mm' in the body to majordomo@xxxxxxxxx. For more info on Linux MM, see: http://www.linux-mm.org/ . Don't email: <a href=mailto:"dont@xxxxxxxxx";> email@xxxxxxxxx </a>