Messages in this thread Patch in this message | | | Date | Mon, 23 May 2022 15:45:33 +0100 | Subject | Re: [PATCH v4 12/13] drm/msm: Utilize gpu scheduler priorities | From | Tvrtko Ursulin <> |
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Hi Rob,
On 28/07/2021 02:06, Rob Clark wrote: > From: Rob Clark <robdclark@chromium.org> > > The drm/scheduler provides additional prioritization on top of that > provided by however many number of ringbuffers (each with their own > priority level) is supported on a given generation. Expose the > additional levels of priority to userspace and map the userspace > priority back to ring (first level of priority) and schedular priority > (additional priority levels within the ring). > > Signed-off-by: Rob Clark <robdclark@chromium.org> > Acked-by: Christian König <christian.koenig@amd.com> > --- > drivers/gpu/drm/msm/adreno/adreno_gpu.c | 4 +- > drivers/gpu/drm/msm/msm_gem_submit.c | 4 +- > drivers/gpu/drm/msm/msm_gpu.h | 58 ++++++++++++++++++++++++- > drivers/gpu/drm/msm/msm_submitqueue.c | 35 +++++++-------- > include/uapi/drm/msm_drm.h | 14 +++++- > 5 files changed, 88 insertions(+), 27 deletions(-) > > diff --git a/drivers/gpu/drm/msm/adreno/adreno_gpu.c b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > index bad4809b68ef..748665232d29 100644 > --- a/drivers/gpu/drm/msm/adreno/adreno_gpu.c > +++ b/drivers/gpu/drm/msm/adreno/adreno_gpu.c > @@ -261,8 +261,8 @@ int adreno_get_param(struct msm_gpu *gpu, uint32_t param, uint64_t *value) > return ret; > } > return -EINVAL; > - case MSM_PARAM_NR_RINGS: > - *value = gpu->nr_rings; > + case MSM_PARAM_PRIORITIES: > + *value = gpu->nr_rings * NR_SCHED_PRIORITIES; > return 0; > case MSM_PARAM_PP_PGTABLE: > *value = 0; > diff --git a/drivers/gpu/drm/msm/msm_gem_submit.c b/drivers/gpu/drm/msm/msm_gem_submit.c > index 450efe59abb5..c2ecec5b11c4 100644 > --- a/drivers/gpu/drm/msm/msm_gem_submit.c > +++ b/drivers/gpu/drm/msm/msm_gem_submit.c > @@ -59,7 +59,7 @@ static struct msm_gem_submit *submit_create(struct drm_device *dev, > submit->gpu = gpu; > submit->cmd = (void *)&submit->bos[nr_bos]; > submit->queue = queue; > - submit->ring = gpu->rb[queue->prio]; > + submit->ring = gpu->rb[queue->ring_nr]; > submit->fault_dumped = false; > > INIT_LIST_HEAD(&submit->node); > @@ -749,7 +749,7 @@ int msm_ioctl_gem_submit(struct drm_device *dev, void *data, > /* Get a unique identifier for the submission for logging purposes */ > submitid = atomic_inc_return(&ident) - 1; > > - ring = gpu->rb[queue->prio]; > + ring = gpu->rb[queue->ring_nr]; > trace_msm_gpu_submit(pid_nr(pid), ring->id, submitid, > args->nr_bos, args->nr_cmds); > > diff --git a/drivers/gpu/drm/msm/msm_gpu.h b/drivers/gpu/drm/msm/msm_gpu.h > index b912cacaecc0..0e4b45bff2e6 100644 > --- a/drivers/gpu/drm/msm/msm_gpu.h > +++ b/drivers/gpu/drm/msm/msm_gpu.h > @@ -250,6 +250,59 @@ struct msm_gpu_perfcntr { > const char *name; > }; > > +/* > + * The number of priority levels provided by drm gpu scheduler. The > + * DRM_SCHED_PRIORITY_KERNEL priority level is treated specially in some > + * cases, so we don't use it (no need for kernel generated jobs). > + */ > +#define NR_SCHED_PRIORITIES (1 + DRM_SCHED_PRIORITY_HIGH - DRM_SCHED_PRIORITY_MIN) > + > +/** > + * msm_gpu_convert_priority - Map userspace priority to ring # and sched priority > + * > + * @gpu: the gpu instance > + * @prio: the userspace priority level > + * @ring_nr: [out] the ringbuffer the userspace priority maps to > + * @sched_prio: [out] the gpu scheduler priority level which the userspace > + * priority maps to > + * > + * With drm/scheduler providing it's own level of prioritization, our total > + * number of available priority levels is (nr_rings * NR_SCHED_PRIORITIES). > + * Each ring is associated with it's own scheduler instance. However, our > + * UABI is that lower numerical values are higher priority. So mapping the > + * single userspace priority level into ring_nr and sched_prio takes some > + * care. The userspace provided priority (when a submitqueue is created) > + * is mapped to ring nr and scheduler priority as such: > + * > + * ring_nr = userspace_prio / NR_SCHED_PRIORITIES > + * sched_prio = NR_SCHED_PRIORITIES - > + * (userspace_prio % NR_SCHED_PRIORITIES) - 1 > + * > + * This allows generations without preemption (nr_rings==1) to have some > + * amount of prioritization, and provides more priority levels for gens > + * that do have preemption.
I am exploring how different drivers handle priority levels and this caught my eye.
Is the implication of the last paragraphs that on hw with nr_rings > 1, ring + 1 preempts ring? If so I am wondering does the "spreading" of user visible priorities by NR_SCHED_PRIORITIES creates a non-preemptable levels within every "bucket" or how does that work?
Regards,
Tvrtko
> + */ > +static inline int msm_gpu_convert_priority(struct msm_gpu *gpu, int prio, > + unsigned *ring_nr, enum drm_sched_priority *sched_prio) > +{ > + unsigned rn, sp; > + > + rn = div_u64_rem(prio, NR_SCHED_PRIORITIES, &sp); > + > + /* invert sched priority to map to higher-numeric-is-higher- > + * priority convention > + */ > + sp = NR_SCHED_PRIORITIES - sp - 1; > + > + if (rn >= gpu->nr_rings) > + return -EINVAL; > + > + *ring_nr = rn; > + *sched_prio = sp; > + > + return 0; > +} > + > /** > * A submitqueue is associated with a gl context or vk queue (or equiv) > * in userspace. > @@ -257,7 +310,8 @@ struct msm_gpu_perfcntr { > * @id: userspace id for the submitqueue, unique within the drm_file > * @flags: userspace flags for the submitqueue, specified at creation > * (currently unusued) > - * @prio: the submitqueue priority > + * @ring_nr: the ringbuffer used by this submitqueue, which is determined > + * by the submitqueue's priority > * @faults: the number of GPU hangs associated with this submitqueue > * @ctx: the per-drm_file context associated with the submitqueue (ie. > * which set of pgtables do submits jobs associated with the > @@ -272,7 +326,7 @@ struct msm_gpu_perfcntr { > struct msm_gpu_submitqueue { > int id; > u32 flags; > - u32 prio; > + u32 ring_nr; > int faults; > struct msm_file_private *ctx; > struct list_head node; > diff --git a/drivers/gpu/drm/msm/msm_submitqueue.c b/drivers/gpu/drm/msm/msm_submitqueue.c > index 682ba2a7c0ec..32a55d81b58b 100644 > --- a/drivers/gpu/drm/msm/msm_submitqueue.c > +++ b/drivers/gpu/drm/msm/msm_submitqueue.c > @@ -68,6 +68,8 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx, > struct msm_gpu_submitqueue *queue; > struct msm_ringbuffer *ring; > struct drm_gpu_scheduler *sched; > + enum drm_sched_priority sched_prio; > + unsigned ring_nr; > int ret; > > if (!ctx) > @@ -76,8 +78,9 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx, > if (!priv->gpu) > return -ENODEV; > > - if (prio >= priv->gpu->nr_rings) > - return -EINVAL; > + ret = msm_gpu_convert_priority(priv->gpu, prio, &ring_nr, &sched_prio); > + if (ret) > + return ret; > > queue = kzalloc(sizeof(*queue), GFP_KERNEL); > > @@ -86,24 +89,13 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx, > > kref_init(&queue->ref); > queue->flags = flags; > - queue->prio = prio; > + queue->ring_nr = ring_nr; > > - ring = priv->gpu->rb[prio]; > + ring = priv->gpu->rb[ring_nr]; > sched = &ring->sched; > > - /* > - * TODO we can allow more priorities than we have ringbuffers by > - * mapping: > - * > - * ring = prio / 3; > - * ent_prio = DRM_SCHED_PRIORITY_MIN + (prio % 3); > - * > - * Probably avoid using DRM_SCHED_PRIORITY_KERNEL as that is > - * treated specially in places. > - */ > ret = drm_sched_entity_init(&queue->entity, > - DRM_SCHED_PRIORITY_NORMAL, > - &sched, 1, NULL); > + sched_prio, &sched, 1, NULL); > if (ret) { > kfree(queue); > return ret; > @@ -134,16 +126,19 @@ int msm_submitqueue_create(struct drm_device *drm, struct msm_file_private *ctx, > int msm_submitqueue_init(struct drm_device *drm, struct msm_file_private *ctx) > { > struct msm_drm_private *priv = drm->dev_private; > - int default_prio; > + int default_prio, max_priority; > > if (!priv->gpu) > return -ENODEV; > > + max_priority = (priv->gpu->nr_rings * NR_SCHED_PRIORITIES) - 1; > + > /* > - * Select priority 2 as the "default priority" unless nr_rings is less > - * than 2 and then pick the lowest priority > + * Pick a medium priority level as default. Lower numeric value is > + * higher priority, so round-up to pick a priority that is not higher > + * than the middle priority level. > */ > - default_prio = clamp_t(uint32_t, 2, 0, priv->gpu->nr_rings - 1); > + default_prio = DIV_ROUND_UP(max_priority, 2); > > INIT_LIST_HEAD(&ctx->submitqueues); > > diff --git a/include/uapi/drm/msm_drm.h b/include/uapi/drm/msm_drm.h > index f075851021c3..6b8fffc28a50 100644 > --- a/include/uapi/drm/msm_drm.h > +++ b/include/uapi/drm/msm_drm.h > @@ -73,11 +73,19 @@ struct drm_msm_timespec { > #define MSM_PARAM_MAX_FREQ 0x04 > #define MSM_PARAM_TIMESTAMP 0x05 > #define MSM_PARAM_GMEM_BASE 0x06 > -#define MSM_PARAM_NR_RINGS 0x07 > +#define MSM_PARAM_PRIORITIES 0x07 /* The # of priority levels */ > #define MSM_PARAM_PP_PGTABLE 0x08 /* => 1 for per-process pagetables, else 0 */ > #define MSM_PARAM_FAULTS 0x09 > #define MSM_PARAM_SUSPENDS 0x0a > > +/* For backwards compat. The original support for preemption was based on > + * a single ring per priority level so # of priority levels equals the # > + * of rings. With drm/scheduler providing additional levels of priority, > + * the number of priorities is greater than the # of rings. The param is > + * renamed to better reflect this. > + */ > +#define MSM_PARAM_NR_RINGS MSM_PARAM_PRIORITIES > + > struct drm_msm_param { > __u32 pipe; /* in, MSM_PIPE_x */ > __u32 param; /* in, MSM_PARAM_x */ > @@ -304,6 +312,10 @@ struct drm_msm_gem_madvise { > > #define MSM_SUBMITQUEUE_FLAGS (0) > > +/* > + * The submitqueue priority should be between 0 and MSM_PARAM_PRIORITIES-1, > + * a lower numeric value is higher priority. > + */ > struct drm_msm_submitqueue { > __u32 flags; /* in, MSM_SUBMITQUEUE_x */ > __u32 prio; /* in, Priority level */
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