On Wed 09-09-20 10:44:32, Aaron Lu wrote: > On Thu, Aug 27, 2020 at 09:40:22PM -0400, Daniel Jordan wrote: > > I went back to your v1 post to see what motivated you originally, and you had > > some results from aim9 but nothing about where this reared its head in the > > first place. How did you discover the bottleneck? I'm just curious about how > > lru_lock hurts in practice. > > I think making lru_lock per-memcg helps in colocated environment: some > workloads are of high priority while some workloads are of low priority. > > For these low priority workloads, we may even want to use some swap for > it to save memory and this can cause frequent alloc/reclaim, depending > on its workingset etc. and these alloc/reclaim need to hold the global > lru lock and zone lock. And then when the high priority workloads do > page fault, their performance can be adversely affected and that is not > acceptible since these high priority workloads normally have strict SLA > requirement. While this all sounds reasonably. We are lacking _any_ numbers to actually make that a solid argumentation rather than hand waving. Having something solid is absolutely necessary for a big change like this. -- Michal Hocko SUSE Labs
