On Tue 23-01-18 17:39:19, Michel Dänzer wrote: > On 2018-01-23 04:36 PM, Michal Hocko wrote: > > On Tue 23-01-18 15:27:00, Roman Gushchin wrote: > >> On Thu, Jan 18, 2018 at 06:00:06PM +0100, Michal Hocko wrote: > >>> On Thu 18-01-18 11:47:48, Andrey Grodzovsky wrote: > >>>> Hi, this series is a revised version of an RFC sent by Christian König > >>>> a few years ago. The original RFC can be found at > >>>> https://urldefense.proofpoint.com/v2/url?u=https-3A__lists.freedesktop.org_archives_dri-2Ddevel_2015-2DSeptember_089778.html&d=DwIDAw&c=5VD0RTtNlTh3ycd41b3MUw&r=jJYgtDM7QT-W-Fz_d29HYQ&m=R-JIQjy8rqmH5qD581_VYL0Q7cpWSITKOnBCE-3LI8U&s=QZGqKpKuJ2BtioFGSy8_721owcWJ0J6c6d4jywOwN4w&; > >>> Here is the origin cover letter text > >>> : I'm currently working on the issue that when device drivers allocate memory on > >>> : behalf of an application the OOM killer usually doesn't knew about that unless > >>> : the application also get this memory mapped into their address space. > >>> : > >>> : This is especially annoying for graphics drivers where a lot of the VRAM > >>> : usually isn't CPU accessible and so doesn't make sense to map into the > >>> : address space of the process using it. > >>> : > >>> : The problem now is that when an application starts to use a lot of VRAM those > >>> : buffers objects sooner or later get swapped out to system memory, but when we > >>> : now run into an out of memory situation the OOM killer obviously doesn't knew > >>> : anything about that memory and so usually kills the wrong process. > >>> : > >>> : The following set of patches tries to address this problem by introducing a per > >>> : file OOM badness score, which device drivers can use to give the OOM killer a > >>> : hint how many resources are bound to a file descriptor so that it can make > >>> : better decisions which process to kill. > >>> : > >>> : So question at every one: What do you think about this approach? > >>> : > >>> : My biggest concern right now is the patches are messing with a core kernel > >>> : structure (adding a field to struct file). Any better idea? I'm considering > >>> : to put a callback into file_ops instead. > >> > >> Hello! > >> > >> I wonder if groupoom (aka cgroup-aware OOM killer) can work for you? > > > > I do not think so. The problem is that the allocating context is not > > identical with the end consumer. > > That's actually not really true. Even in cases where a BO is shared with > a different process, it is still used at least occasionally in the > process which allocated it as well. Otherwise there would be no point in > sharing it between processes. OK, but somebody has to be made responsible. Otherwise you are just killing a process which doesn't really release any memory. > There should be no problem if the memory of a shared BO is accounted for > in each process sharing it. It might be nice to scale each process' > "debt" by 1 / (number of processes sharing it) if possible, but in the > worst case accounting it fully in each process should be fine. So how exactly then helps to kill one of those processes? The memory stays pinned behind or do I still misunderstand? -- Michal Hocko SUSE Labs
