On Thu 26-04-18 14:00:19, Kirill Tkhai wrote: > This function searches for a new mm owner in children and siblings, > and then iterates over all processes in the system in unlikely case. > Despite the case is unlikely, its probability growths with the number > of processes in the system. The time, spent on iterations, also growths. > I regulary observe mm_update_next_owner() in crash dumps (not related > to this function) of the nodes with many processes (20K+), so it looks > like it's not so unlikely case.
Did you manage to find the pattern that forces mm_update_next_owner to slow paths? This really shouldn't trigger very often. If we can fallback easily then I suspect that we should be better off reconsidering mm->owner and try to come up with something more clever. I've had a patch to remove owner few years back. It needed some work to finish but maybe that would be a better than try to make non-scalable thing suck less. -- Michal Hocko SUSE Labs
