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@ffwll.ch 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.
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