Re: [RFC PATCH 0/5] cgroup support for GPU devices

[Leon Romanovsky <leon@kernel.org>]

On Wed, May 01, 2019 at 10:04:33AM -0400, Brian Welty wrote:
> In containerized or virtualized environments, there is desire to have
> controls in place for resources that can be consumed by users of a GPU
> device.  This RFC patch series proposes a framework for integrating
> use of existing cgroup controllers into device drivers.
> The i915 driver is updated in this series as our primary use case to
> leverage this framework and to serve as an example for discussion.
>
> The patch series enables device drivers to use cgroups to control the
> following resources within a GPU (or other accelerator device):
> *  control allocation of device memory (reuse of memcg)

Count us (Mellanox) too, our RDMA devices are exposing special and
limited in size device memory to the users and we would like to provide
an option to use cgroup to control its exposure.

> and with future work, we could extend to:
> *  track and control share of GPU time (reuse of cpu/cpuacct)
> *  apply mask of allowed execution engines (reuse of cpusets)
>
> Instead of introducing a new cgroup subsystem for GPU devices, a new
> framework is proposed to allow devices to register with existing cgroup
> controllers, which creates per-device cgroup_subsys_state within the
> cgroup.  This gives device drivers their own private cgroup controls
> (such as memory limits or other parameters) to be applied to device
> resources instead of host system resources.
> Device drivers (GPU or other) are then able to reuse the existing cgroup
> controls, instead of inventing similar ones.
>
> Per-device controls would be exposed in cgroup filesystem as:
>     mount/<cgroup_name>/<subsys_name>.devices/<dev_name>/<subsys_files>
> such as (for example):
>     mount/<cgroup_name>/memory.devices/<dev_name>/memory.max
>     mount/<cgroup_name>/memory.devices/<dev_name>/memory.current
>     mount/<cgroup_name>/cpu.devices/<dev_name>/cpu.stat
>     mount/<cgroup_name>/cpu.devices/<dev_name>/cpu.weight
>
> The drm/i915 patch in this series is based on top of other RFC work [1]
> for i915 device memory support.
>
> AMD [2] and Intel [3] have proposed related work in this area within the
> last few years, listed below as reference.  This new RFC reuses existing
> cgroup controllers and takes a different approach than prior work.
>
> Finally, some potential discussion points for this series:
> * merge proposed <subsys_name>.devices into a single devices directory?
> * allow devices to have multiple registrations for subsets of resources?
> * document a 'common charging policy' for device drivers to follow?
>
> [1] https://patchwork.freedesktop.org/series/56683/
> [2] https://lists.freedesktop.org/archives/dri-devel/2018-November/197106.html
> [3] https://lists.freedesktop.org/archives/intel-gfx/2018-January/153156.html
>
>
> Brian Welty (5):
>   cgroup: Add cgroup_subsys per-device registration framework
>   cgroup: Change kernfs_node for directories to store
>     cgroup_subsys_state
>   memcg: Add per-device support to memory cgroup subsystem
>   drm: Add memory cgroup registration and DRIVER_CGROUPS feature bit
>   drm/i915: Use memory cgroup for enforcing device memory limit
>
>  drivers/gpu/drm/drm_drv.c                  |  12 +
>  drivers/gpu/drm/drm_gem.c                  |   7 +
>  drivers/gpu/drm/i915/i915_drv.c            |   2 +-
>  drivers/gpu/drm/i915/intel_memory_region.c |  24 +-
>  include/drm/drm_device.h                   |   3 +
>  include/drm/drm_drv.h                      |   8 +
>  include/drm/drm_gem.h                      |  11 +
>  include/linux/cgroup-defs.h                |  28 ++
>  include/linux/cgroup.h                     |   3 +
>  include/linux/memcontrol.h                 |  10 +
>  kernel/cgroup/cgroup-v1.c                  |  10 +-
>  kernel/cgroup/cgroup.c                     | 310 ++++++++++++++++++---
>  mm/memcontrol.c                            | 183 +++++++++++-
>  13 files changed, 552 insertions(+), 59 deletions(-)
>
> --
> 2.21.0
>