On 2018-04-04 11:36 AM, Lucas Stach wrote: > Am Mittwoch, den 04.04.2018, 11:09 +0200 schrieb Michel Dänzer: >> On 2018-03-26 04:36 PM, Lucas Stach wrote: >>> Am Dienstag, den 30.01.2018, 11:28 +0100 schrieb Michal Hocko: >>>> On Tue 30-01-18 10:29:10, Michel Dänzer wrote: >>>>> On 2018-01-24 12:50 PM, Michal Hocko wrote: >>>>>> On Wed 24-01-18 12:23:10, Michel Dänzer wrote: >>>>>>> On 2018-01-24 12:01 PM, Michal Hocko wrote: >>>>>>>> On Wed 24-01-18 11:27:15, Michel Dänzer wrote: >>>>>> >>>>>> [...] >>>>>>>>> 2. If the OOM killer kills a process which is sharing BOs >>>>>>>>> with another >>>>>>>>> process, this should result in the other process dropping >>>>>>>>> its references >>>>>>>>> to the BOs as well, at which point the memory is released. >>>>>>>> >>>>>>>> OK. How exactly are those BOs mapped to the userspace? >>>>>>> >>>>>>> I'm not sure what you're asking. Userspace mostly uses a GEM >>>>>>> handle to >>>>>>> refer to a BO. There can also be userspace CPU mappings of the >>>>>>> BO's >>>>>>> memory, but userspace doesn't need CPU mappings for all BOs and >>>>>>> only >>>>>>> creates them as needed. >>>>>> >>>>>> OK, I guess you have to bear with me some more. This whole stack >>>>>> is a >>>>>> complete uknonwn. I am mostly after finding a boundary where you >>>>>> can >>>>>> charge the allocated memory to the process so that the oom killer >>>>>> can >>>>>> consider it. Is there anything like that? Except for the proposed >>>>>> file >>>>>> handle hack? >>>>> >>>>> How about the other way around: what APIs can we use to charge / >>>>> "uncharge" memory to a process? If we have those, we can experiment >>>>> with >>>>> different places to call them. >>>> >>>> add_mm_counter() and I would add a new counter e.g. MM_KERNEL_PAGES. >>> >>> So is anyone still working on this? This is hurting us bad enough that >>> I don't want to keep this topic rotting for another year. >>> >>> If no one is currently working on this I would volunteer to give the >>> simple "just account private, non-shared buffers in process RSS" a >>> spin. >> >> Sounds good. FWIW, I think shared buffers can also be easily handled by >> accounting them in each process which has a reference. But that's more >> of a detail, shouldn't make a big difference overall either way. > > Yes, both options to wither never account shared buffers or to always > account them into every process having a reference should be pretty > easy. Where it gets hard is when trying to account the buffer only in > the last process holding a reference or something like this. FWIW, I don't think that would make sense anyway. A shared buffer is actually used by all processes which have a reference to it, so it should be accounted the same in all of them. -- Earthling Michel Dänzer | http://www.amd.com Libre software enthusiast | Mesa and X developer
