On 3/9/22 22:28, Thomas Zimmermann wrote: > Hi > > Am 09.03.22 um 12:55 schrieb Dmitry Osipenko: >> Hello, >> >> On 3/9/22 11:59, Thomas Zimmermann wrote: >>> Hi >>> >>> Am 08.03.22 um 14:17 schrieb Dmitry Osipenko: >>>> Hello, >>>> >>>> This patchset introduces memory shrinker for the VirtIO-GPU DRM driver. >>>> During OOM, the shrinker will release BOs that are marked as "not >>>> needed" >>>> by userspace using the new madvise IOCTL. The userspace in this case is >>>> the Mesa VirGL driver, it will mark the cached BOs as "not needed", >>>> allowing kernel driver to release memory of the cached shmem BOs on >>>> lowmem >>>> situations, preventing OOM kills. >>> >>> Virtio-gpu is build on top of GEM shmem helpers. I have a prototype >>> patchset that adds a shrinker to these helpers. If you want to go >>> further, you could implement something like that instead. Panfrost and >>> lima also have their own shrinker and could certainly be converted to >>> the gem-shmem shrinker. >> >> I had a thought that it could be possible to unify shrinkers into a >> common DRM framework. Could you please give me a link to yours prototype >> patchset? > > I uploaded the patches to > > > https://gitlab.freedesktop.org/tzimmermann/linux/-/commits/gem-shmem-cached-mappings > > > it's incomplete and un-debugged, but it shows what needs to be done. It > has the infrastructure, but lacks the changes to the GEM shmem code. > > The reason for this work is to keep GEM shmem pages mapped and allocated > even while the BO is neither mapped nor pinned. As it is now, GEM SHMEM > creates and releases pages on each pin and unpin, and maps and unmaps > memory ranges on each vmap and vunmap. It's all wasteful. Only the > first pin and vmap calls should establish pages and mappings and only > the purge and free functions should release them. Hm, aren't maps and pins already refcounted? > The patchset adds new helpers for BO purging to struct > drm_gem_object_funcs. With this, I think it might be possible to have > one global DRM shrinker and let it handle all BOs; independent of each > BO's memory manager. Thank you, I'll give it a try.
