On Fri, May 7, 2021 at 7:45 PM Tejun Heo <tj@xxxxxxxxxx> wrote: > > Hello, > > On Fri, May 07, 2021 at 06:30:56PM -0400, Alex Deucher wrote: > > Maybe we are speaking past each other. I'm not following. We got > > here because a device specific cgroup didn't make sense. With my > > Linux user hat on, that makes sense. I don't want to write code to a > > bunch of device specific interfaces if I can avoid it. But as for > > temporal vs spatial partitioning of the GPU, the argument seems to be > > a sort of hand-wavy one that both spatial and temporal partitioning > > make sense on CPUs, but only temporal partitioning makes sense on > > GPUs. I'm trying to understand that assertion. There are some GPUs > > Spatial partitioning as implemented in cpuset isn't a desirable model. It's > there partly because it has historically been there. It doesn't really > require dynamic hierarchical distribution of anything and is more of a way > to batch-update per-task configuration, which is how it's actually > implemented. It's broken too in that it interferes with per-task affinity > settings. So, not exactly a good example to follow. In addition, this sort > of partitioning requires more hardware knowledge and GPUs are worse than > CPUs in that hardwares differ more. > > Features like this are trivial to implement from userland side by making > per-process settings inheritable and restricting who can update the > settings. > > > that can more easily be temporally partitioned and some that can be > > more easily spatially partitioned. It doesn't seem any different than > > CPUs. > > Right, it doesn't really matter how the resource is distributed. What > matters is how granular and generic the distribution can be. If gpus can > implement work-conserving proportional distribution, that's something which > is widely useful and inherently requires dynamic scheduling from kernel > side. If it's about setting per-vendor affinities, this is way too much > cgroup interface for a feature which can be easily implemented outside > cgroup. Just do per-process (or whatever handles gpus use) and confine their > configurations from cgroup side however way. > > While the specific theme changes a bit, we're basically having the same > discussion with the same conclusion over the past however many months. > Hopefully, the point is clear by now. Thanks, that helps a lot. Alex
