On Wed 24-07-19 16:37:35, Tetsuo Handa wrote: > On 2019/07/24 15:41, Michal Hocko wrote: [...] > > That being said, I do not think this patch gives any improvement. > > > > This patch avoids RCU during select_bad_process(). It just shifts where the RCU is taken. Do you have any numbers to show that this is an improvement? Basically the only potentially expensive thing down the oom_evaluate_task that I can see is the task_lock but I am not aware of a single report that this would be a contributor for RCU stalls. I can be proven wrong but > This patch allows > possibility of doing reschedulable things there; e.g. directly reaping > only a portion of OOM victim's memory rather than wasting CPU resource > by spinning until MMF_OOM_SKIP is set by the OOM reaper. We have been through direct oom reaping before and I haven't changed my possition there. It is just too tricky to be worth it. -- Michal Hocko SUSE Labs
