[RFC] Add BPF_PROG_TYPE_CGROUP_IOCTL

[Alex Deucher]

On Fri, May 7, 2021 at 3:33 PM Tejun Heo <tj at kernel.org> wrote:
>
> Hello,
>
> On Fri, May 07, 2021 at 06:54:13PM +0200, Daniel Vetter wrote:
> > 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.
>
> FWIW, I'm completely on the same boat. There are two fundamental issues with
> hardware-mask based control - control granularity and work conservation.
> Combined, they make it a significantly more difficult interface to use which
> requires hardware-specific tuning rather than simply being able to say "I
> wanna prioritize this job twice over that one".
>
> My knoweldge of gpus is really limited but my understanding is also that the
> gpu cores and threads aren't as homogeneous as the CPU counterparts across
> the vendors, product generations and possibly even within a single chip,
> which makes the problem even worse.
>
> Given that GPUs are time-shareable to begin with, the most universal
> solution seems pretty clear.

The problem is temporal partitioning on GPUs is much harder to enforce
unless you have a special case like SR-IOV.  Spatial partitioning, on
AMD GPUs at least, is widely available and easily enforced.  What is
the point of implementing temporal style cgroups if no one can enforce
it effectively?

Alex

>
> Thanks.
>
> --
> tejun