On Sun, Jun 30, 2019 at 01:10:28AM -0400, Kenny Ho wrote: > On Thu, Jun 27, 2019 at 3:24 AM Daniel Vetter <daniel@xxxxxxxx> wrote: > > Another question I have: What about HMM? With the device memory zone > > the core mm will be a lot more involved in managing that, but I also > > expect that we'll have classic buffer-based management for a long time > > still. So these need to work together, and I fear slightly that we'll > > have memcg and drmcg fighting over the same pieces a bit perhaps? > > > > Adding Jerome, maybe he has some thoughts on this. > > I just did a bit of digging and this looks like the current behaviour: > https://www.kernel.org/doc/html/v5.1/vm/hmm.html#memory-cgroup-memcg-and-rss-accounting > > "For now device memory is accounted as any regular page in rss > counters (either anonymous if device page is used for anonymous, file > if device page is used for file backed page or shmem if device page is > used for shared memory). This is a deliberate choice to keep existing > applications, that might start using device memory without knowing > about it, running unimpacted. > > A drawback is that the OOM killer might kill an application using a > lot of device memory and not a lot of regular system memory and thus > not freeing much system memory. We want to gather more real world > experience on how applications and system react under memory pressure > in the presence of device memory before deciding to account device > memory differently." Hm ... I also just learned that the device memory stuff, at least the hmm part, is probably getting removed again, and only the hmm_mirror part of hmm will be kept. So maybe this doesn't matter to us. But really no idea. -Daniel -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
