Quoting Brian Welty (2021-01-26 23:46:24)
> Single control below is added to DRM cgroup controller in order to track
> user execution time for GPU devices. It is up to device drivers to
> charge execution time to the cgroup via drm_cgroup_try_charge().
>
> sched.runtime
> Read-only value, displays current user execution time for each DRM
> device. The expectation is that this is incremented by DRM device
> driver's scheduler upon user context completion or context switch.
> Units of time are in microseconds for consistency with cpu.stats.
Were not we also planning for a percentage style budgeting?
Capping the maximum runtime is definitely useful, but in order to
configure a system for peaceful co-existence of two or more workloads we
must also impose a limit on how big portion of the instantaneous
capacity can be used.
Regards, Joonas
> Signed-off-by: Brian Welty <brian.welty@xxxxxxxxx>
> ---
> Documentation/admin-guide/cgroup-v2.rst | 9 +++++++++
> include/drm/drm_cgroup.h | 2 ++
> include/linux/cgroup_drm.h | 2 ++
> kernel/cgroup/drm.c | 20 ++++++++++++++++++++
> 4 files changed, 33 insertions(+)
>
> diff --git a/Documentation/admin-guide/cgroup-v2.rst b/Documentation/admin-guide/cgroup-v2.rst
> index ccc25f03a898..f1d0f333a49e 100644
> --- a/Documentation/admin-guide/cgroup-v2.rst
> +++ b/Documentation/admin-guide/cgroup-v2.rst
> @@ -2205,6 +2205,15 @@ thresholds are hit, this would then allow the DRM device driver to invoke
> some equivalent to OOM-killer or forced memory eviction for the device
> backed memory in order to attempt to free additional space.
>
> +The below set of control files are for time accounting of DRM devices. Units
> +of time are in microseconds.
> +
> + sched.runtime
> + Read-only value, displays current user execution time for each DRM
> + device. The expectation is that this is incremented by DRM device
> + driver's scheduler upon user context completion or context switch.
> +
> +
> Misc
> ----
>
> diff --git a/include/drm/drm_cgroup.h b/include/drm/drm_cgroup.h
> index 9ba0e372eeee..315dab8a93b8 100644
> --- a/include/drm/drm_cgroup.h
> +++ b/include/drm/drm_cgroup.h
> @@ -22,6 +22,7 @@ enum drmcg_res_type {
> DRMCG_TYPE_MEM_CURRENT,
> DRMCG_TYPE_MEM_MAX,
> DRMCG_TYPE_MEM_TOTAL,
> + DRMCG_TYPE_SCHED_RUNTIME,
> __DRMCG_TYPE_LAST,
> };
>
> @@ -79,5 +80,6 @@ void drm_cgroup_uncharge(struct drmcg *drmcg,struct drm_device *dev,
> enum drmcg_res_type type, u64 usage)
> {
> }
> +
> #endif /* CONFIG_CGROUP_DRM */
> #endif /* __DRM_CGROUP_H__ */
> diff --git a/include/linux/cgroup_drm.h b/include/linux/cgroup_drm.h
> index 3570636473cf..0fafa663321e 100644
> --- a/include/linux/cgroup_drm.h
> +++ b/include/linux/cgroup_drm.h
> @@ -19,6 +19,8 @@
> */
> struct drmcg_device_resource {
> struct page_counter memory;
> + seqlock_t sched_lock;
> + u64 exec_runtime;
> };
>
> /**
> diff --git a/kernel/cgroup/drm.c b/kernel/cgroup/drm.c
> index 08e75eb67593..64e9d0dbe8c8 100644
> --- a/kernel/cgroup/drm.c
> +++ b/kernel/cgroup/drm.c
> @@ -81,6 +81,7 @@ static inline int init_drmcg_single(struct drmcg *drmcg, struct drm_device *dev)
> /* set defaults here */
> page_counter_init(&ddr->memory,
> parent_ddr ? &parent_ddr->memory : NULL);
> + seqlock_init(&ddr->sched_lock);
> drmcg->dev_resources[minor] = ddr;
>
> return 0;
> @@ -287,6 +288,10 @@ static int drmcg_seq_show_fn(int id, void *ptr, void *data)
> seq_printf(sf, "%d:%d %llu\n", DRM_MAJOR, minor->index,
> minor->dev->drmcg_props.memory_total);
> break;
> + case DRMCG_TYPE_SCHED_RUNTIME:
> + seq_printf(sf, "%d:%d %llu\n", DRM_MAJOR, minor->index,
> + ktime_to_us(ddr->exec_runtime));
> + break;
> default:
> seq_printf(sf, "%d:%d\n", DRM_MAJOR, minor->index);
> break;
> @@ -384,6 +389,12 @@ struct cftype files[] = {
> .private = DRMCG_TYPE_MEM_TOTAL,
> .flags = CFTYPE_ONLY_ON_ROOT,
> },
> + {
> + .name = "sched.runtime",
> + .seq_show = drmcg_seq_show,
> + .private = DRMCG_TYPE_SCHED_RUNTIME,
> + .flags = CFTYPE_NOT_ON_ROOT,
> + },
> { } /* terminate */
> };
>
> @@ -440,6 +451,10 @@ EXPORT_SYMBOL(drmcg_device_early_init);
> * choose to enact some form of memory reclaim, but the exact behavior is left
> * to the DRM device driver to define.
> *
> + * For @res type of DRMCG_TYPE_SCHED_RUNTIME:
> + * For GPU time accounting, add @usage amount of GPU time to @drmcg for
> + * the given device.
> + *
> * Returns 0 on success. Otherwise, an error code is returned.
> */
> int drm_cgroup_try_charge(struct drmcg *drmcg, struct drm_device *dev,
> @@ -466,6 +481,11 @@ int drm_cgroup_try_charge(struct drmcg *drmcg, struct drm_device *dev,
> err = 0;
> }
> break;
> + case DRMCG_TYPE_SCHED_RUNTIME:
> + write_seqlock(&res->sched_lock);
> + res->exec_runtime = ktime_add(res->exec_runtime, usage);
> + write_sequnlock(&res->sched_lock);
> + break;
> default:
> err = -EINVAL;
> break;
> --
> 2.20.1
>
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