On Tue, 4 May 2021 17:37:32 Shakeel Butt wrote: >On Wed, Apr 21, 2021 at 7:29 AM Michal Hocko <mhocko@xxxxxxxx> wrote: >[...] >> > > What if the pool is depleted? >> > >> > This would mean that either the estimate of mempool size is bad or >> > oom-killer is buggy and leaking memory. >> > >> > I am open to any design directions for mempool or some other way where >> > we can provide a notion of memory guarantee to oom-killer. >> >> OK, thanks for clarification. There will certainly be hard problems to >> sort out[1] but the overall idea makes sense to me and it sounds like a >> much better approach than a OOM specific solution. >> >> >> [1] - how the pool is going to be replenished without hitting all >> potential reclaim problems (thus dependencies on other all tasks >> directly/indirectly) yet to not rely on any background workers to do >> that on the task behalf without a proper accounting etc... >> -- > >I am currently contemplating between two paths here: > >First, the mempool, exposed through either prctl or a new syscall. >Users would need to trace their userspace oom-killer (or whatever >their use case is) to find an appropriate mempool size they would need >and periodically refill the mempools if allowed by the state of the >machine. The challenge here is to find a good value for the mempool >size and coordinating the refilling of mempools. > >Second is a mix of Roman and Peter's suggestions but much more >simplified. A very simple watchdog with a kill-list of processes and >if userspace didn't pet the watchdog within a specified time, it will >kill all the processes in the kill-list. The challenge here is to >maintain/update the kill-list. > >I would prefer the direction which oomd and lmkd are open to adopt. > >Any suggestions? > The kill list is drained once the wd starts doing its job AFAICT, would you likely specify a bit on what matters if a process goes home before waking up the wd? What will happen if it would signal the pid of a non-existing one with the consequences all ignored? Other than that, what is in your mind over the challenge to maintain the kill-list? Hillf
