On Fri, May 07, 2021 at 12:50:07PM -0400, Alex Deucher wrote: > On Fri, May 7, 2021 at 12:31 PM Alex Deucher <alexdeucher@xxxxxxxxx> wrote: > > > > On Fri, May 7, 2021 at 12:26 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > On Fri, May 07, 2021 at 12:19:13PM -0400, Alex Deucher wrote: > > > > On Fri, May 7, 2021 at 12:13 PM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > > > > > On Fri, May 07, 2021 at 11:33:46AM -0400, Kenny Ho wrote: > > > > > > On Fri, May 7, 2021 at 4:59 AM Daniel Vetter <daniel@xxxxxxxx> wrote: > > > > > > > > > > > > > > Hm I missed that. I feel like time-sliced-of-a-whole gpu is the easier gpu > > > > > > > cgroups controler to get started, since it's much closer to other cgroups > > > > > > > that control bandwidth of some kind. Whether it's i/o bandwidth or compute > > > > > > > bandwidht is kinda a wash. > > > > > > sriov/time-sliced-of-a-whole gpu does not really need a cgroup > > > > > > interface since each slice appears as a stand alone device. This is > > > > > > already in production (not using cgroup) with users. The cgroup > > > > > > proposal has always been parallel to that in many sense: 1) spatial > > > > > > partitioning as an independent but equally valid use case as time > > > > > > sharing, 2) sub-device resource control as opposed to full device > > > > > > control motivated by the workload characterization paper. It was > > > > > > never about time vs space in terms of use cases but having new API for > > > > > > users to be able to do spatial subdevice partitioning. > > > > > > > > > > > > > CU mask feels a lot more like an isolation/guaranteed forward progress > > > > > > > kind of thing, and I suspect that's always going to be a lot more gpu hw > > > > > > > specific than anything we can reasonably put into a general cgroups > > > > > > > controller. > > > > > > The first half is correct but I disagree with the conclusion. The > > > > > > analogy I would use is multi-core CPU. The capability of individual > > > > > > CPU cores, core count and core arrangement may be hw specific but > > > > > > there are general interfaces to support selection of these cores. CU > > > > > > mask may be hw specific but spatial partitioning as an idea is not. > > > > > > Most gpu vendors have the concept of sub-device compute units (EU, SE, > > > > > > etc.); OpenCL has the concept of subdevice in the language. I don't > > > > > > see any obstacle for vendors to implement spatial partitioning just > > > > > > like many CPU vendors support the idea of multi-core. > > > > > > > > > > > > > Also for the time slice cgroups thing, can you pls give me pointers to > > > > > > > these old patches that had it, and how it's done? I very obviously missed > > > > > > > that part. > > > > > > I think you misunderstood what I wrote earlier. The original proposal > > > > > > was about spatial partitioning of subdevice resources not time sharing > > > > > > using cgroup (since time sharing is already supported elsewhere.) > > > > > > > > > > Well SRIOV time-sharing is for virtualization. cgroups is for > > > > > containerization, which is just virtualization but with less overhead and > > > > > more security bugs. > > > > > > > > > > More or less. > > > > > > > > > > So either I get things still wrong, or we'll get time-sharing for > > > > > virtualization, and partitioning of CU for containerization. That doesn't > > > > > make that much sense to me. > > > > > > > > You could still potentially do SR-IOV for containerization. You'd > > > > just pass one of the PCI VFs (virtual functions) to the container and > > > > you'd automatically get the time slice. I don't see why cgroups would > > > > be a factor there. > > > > > > Standard interface to manage that time-slicing. I guess for SRIOV it's all > > > vendor sauce (intel as guilty as anyone else from what I can see), but for > > > cgroups that feels like it's falling a bit short of what we should aim > > > for. > > > > > > But dunno, maybe I'm just dreaming too much :-) > > > > I don't disagree, I'm just not sure how it would apply to SR-IOV. > > Once you've created the virtual functions, you've already created the > > partitioning (regardless of whether it's spatial or temporal) so where > > would cgroups come into play? > > For some background, the SR-IOV virtual functions show up like actual > PCI endpoints on the bus, so SR-IOV is sort of like cgroups > implemented in hardware. When you enable SR-IOV, the endpoints that > are created are the partitions. Yeah I think we're massively agreeing right now :-) SRIOV is kinda by design vendor specific. You set up the VF endpoint, it shows up, it's all hw+fw magic. Nothing for cgroups to manage here at all. All I meant is that for the container/cgroups world starting out with time-sharing feels like the best fit, least because your SRIOV designers also seem to think that's the best first cut for cloud-y computing. Whether it's virtualized or containerized is a distinction that's getting ever more blurry, with virtualization become a lot more dynamic and container runtimes als possibly using hw virtualization underneath. -Daniel > > Alex > > > > > Alex > > > > > -Daniel > > > > > > > Alex > > > > > > > > > > > > > > Since time-sharing is the first thing that's done for virtualization I > > > > > think it's probably also the most reasonable to start with for containers. > > > > > -Daniel > > > > > -- > > > > > Daniel Vetter > > > > > Software Engineer, Intel Corporation > > > > > http://blog.ffwll.ch > > > > > _______________________________________________ > > > > > amd-gfx mailing list > > > > > amd-gfx@xxxxxxxxxxxxxxxxxxxxx > > > > > https://lists.freedesktop.org/mailman/listinfo/amd-gfx > > > > > > -- > > > Daniel Vetter > > > Software Engineer, Intel Corporation > > > http://blog.ffwll.ch -- Daniel Vetter Software Engineer, Intel Corporation http://blog.ffwll.ch
