On Sun 01-10-17 16:29:48, Shakeel Butt wrote: > > > > Going back to Michal's example, say the user configured the following: > > > > root > > / \ > > A D > > / \ > > B C > > > > A global OOM event happens and we find this: > > - A > D > > - B, C, D are oomgroups > > > > What the user is telling us is that B, C, and D are compound memory > > consumers. They cannot be divided into their task parts from a memory > > point of view. > > > > However, the user doesn't say the same for A: the A subtree summarizes > > and controls aggregate consumption of B and C, but without groupoom > > set on A, the user says that A is in fact divisible into independent > > memory consumers B and C. > > > > If we don't have to kill all of A, but we'd have to kill all of D, > > does it make sense to compare the two? > > > > I think Tim has given very clear explanation why comparing A & D makes > perfect sense. However I think the above example, a single user system > where a user has designed and created the whole hierarchy and then > attaches different jobs/applications to different nodes in this > hierarchy, is also a valid scenario. Yes and nobody is disputing that, really. I guess the main disconnect here is that different people want to have more detailed control over the victim selection while the patchset tries to handle the most simplistic scenario when a no userspace control over the selection is required. And I would claim that this will be a last majority of setups and we should address it first. A more fine grained control needs some more thinking to come up with a sensible and long term sustainable API. Just look back and see at the oom_score_adj story and how it ended up unusable in the end (well apart from never/always kill corner cases). Let's not repeat that again now. I strongly believe that we can come up with something - be it priority based, BFP based or module based selection. But let's start simple with the most basic scenario first with a most sensible semantic implemented. I believe the latest version (v9) looks sensible from the semantic point of view and we should focus on making it into a mergeable shape. -- 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>
