Question about per process GPU context global priority enforcement

[Yiwei Zhang]

Let me add more context. On Android, systemui and launcher should be
allowed to create high priority gpu contexts while the normal random
applications must be ceiled to default priority. However, systemui and
launcher are not allowed to create realtime threads so we can't grant
them CAP_SYS_NICE. Thus either a new cgroup is needed in this case or
we add sysui/launcher into some other present cgroup for the gfx
kernel driver to distinguish.

On Wed, Aug 5, 2020 at 4:47 AM Bas Nieuwenhuizen
<bas at basnieuwenhuizen.nl> wrote:
>
> I don't think we have a uniform mechanism, currently each driver
> decides on their own.
>
> For the amdgpu driver we check that the process either has
> CAP_SYS_NICE or is the DRM master.
>
> On Wed, Aug 5, 2020 at 9:14 AM Yiwei Zhang <zzyiwei at google.com> wrote:
> >
> > Hi friends,
> >
> > For Vulkan/EGL, upon creating gpu contexts, applications can ask for a
> > system-wide higher priority levels via VK_EXT_global_priority or
> > EGL_IMG_context_priority extensions.
> >
> > I'm curious if we have certain rules(some form of process privilege
> > check) in the kernel to limit non-privileged ones to never go beyond
> > default system-wide gpu scheduling priority. (e.g. not allow random
> > app processes to contend the GPU queues repeatedly/infinitely with
> > high/realtime priorities)
> >
> > Many thanks,
> > Yiwei - from Android Platform Graphics Team
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