linux-stable.git/include/drm/gpu_scheduler.h, branch v6.8

drm/sched: Reverse run-queue priority enumeration

2023-11-25T04:03:53+00:00

Reverse run-queue priority enumeration such that the higest priority is now 0,
and for each consecutive integer the prioirty diminishes.

Run-queues correspond to priorities. To an external observer a scheduler
created with a single run-queue, and another created with
DRM_SCHED_PRIORITY_COUNT number of run-queues, should always schedule
sched->sched_rq[0] with the same "priority", as that index run-queue exists in
both schedulers, i.e. a scheduler with one run-queue or many. This patch makes
it so.

In other words, the "priority" of sched->sched_rq[n], n >= 0, is the same for
any scheduler created with any allowable number of run-queues (priorities), 0
to DRM_SCHED_PRIORITY_COUNT.

Cc: Rob Clark 
Cc: Abhinav Kumar 
Cc: Dmitry Baryshkov 
Cc: Danilo Krummrich 
Cc: Alex Deucher 
Cc: Christian König 
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Luben Tuikov 
Reviewed-by: Christian König 
Link: https://patchwork.freedesktop.org/patch/msgid/20231124052752.6915-6-ltuikov89@gmail.com

drm/sched: Rename priority MIN to LOW

2023-11-25T04:03:53+00:00

Rename DRM_SCHED_PRIORITY_MIN to DRM_SCHED_PRIORITY_LOW.

This mirrors DRM_SCHED_PRIORITY_HIGH, for a list of DRM scheduler priorities
in ascending order,
  DRM_SCHED_PRIORITY_LOW,
  DRM_SCHED_PRIORITY_NORMAL,
  DRM_SCHED_PRIORITY_HIGH,
  DRM_SCHED_PRIORITY_KERNEL.

Cc: Rob Clark 
Cc: Abhinav Kumar 
Cc: Dmitry Baryshkov 
Cc: Danilo Krummrich 
Cc: Alex Deucher 
Cc: Christian König 
Cc: linux-arm-msm@vger.kernel.org
Cc: freedreno@lists.freedesktop.org
Cc: dri-devel@lists.freedesktop.org
Signed-off-by: Luben Tuikov 
Reviewed-by: Christian König 
Link: https://patchwork.freedesktop.org/patch/msgid/20231124052752.6915-5-ltuikov89@gmail.com

Merge drm/drm-next into drm-misc-next

2023-11-15T09:56:44+00:00

Let's kickstart the v6.8 release cycle.

Signed-off-by: Maxime Ripard

drm/sched: implement dynamic job-flow control

2023-11-10T01:54:29+00:00

Currently, job flow control is implemented simply by limiting the number
of jobs in flight. Therefore, a scheduler is initialized with a credit
limit that corresponds to the number of jobs which can be sent to the
hardware.

This implies that for each job, drivers need to account for the maximum
job size possible in order to not overflow the ring buffer.

However, there are drivers, such as Nouveau, where the job size has a
rather large range. For such drivers it can easily happen that job
submissions not even filling the ring by 1% can block subsequent
submissions, which, in the worst case, can lead to the ring run dry.

In order to overcome this issue, allow for tracking the actual job size
instead of the number of jobs. Therefore, add a field to track a job's
credit count, which represents the number of credits a job contributes
to the scheduler's credit limit.

Signed-off-by: Danilo Krummrich 
Reviewed-by: Luben Tuikov 
Link: https://patchwork.freedesktop.org/patch/msgid/20231110001638.71750-1-dakr@redhat.com

drm/sched: Qualify drm_sched_wakeup() by drm_sched_entity_is_ready()

2023-11-10T00:05:35+00:00

Don't "wake up" the GPU scheduler unless the entity is ready, as well as we
can queue to the scheduler, i.e. there is no point in waking up the scheduler
for the entity unless the entity is ready.

Signed-off-by: Luben Tuikov 
Fixes: bc8d6a9df99038 ("drm/sched: Don't disturb the entity when in RR-mode scheduling")
Reviewed-by: Danilo Krummrich 
Link: https://patchwork.freedesktop.org/patch/msgid/20231110000123.72565-2-ltuikov89@gmail.com

drm/sched: Drop suffix from drm_sched_wakeup_if_can_queue

2023-11-05T01:18:47+00:00

Because a) helper is exported to other parts of the scheduler and
b) there isn't a plain drm_sched_wakeup to begin with, I think we can
drop the suffix and by doing so separate the intimiate knowledge
between the scheduler components a bit better.

Signed-off-by: Tvrtko Ursulin 
Cc: Luben Tuikov 
Cc: Matthew Brost 
Link: https://patchwork.freedesktop.org/patch/msgid/20231102105538.391648-6-tvrtko.ursulin@linux.intel.com
Reviewed-by: Luben Tuikov 
Signed-off-by: Luben Tuikov

drm/sched: Add a helper to queue TDR immediately

2023-11-01T21:29:23+00:00

Add a helper whereby a driver can invoke TDR immediately.

v2:
 - Drop timeout args, rename function, use mod delayed work (Luben)
v3:
 - s/XE/Xe (Luben)
 - present tense in commit message (Luben)
 - Adjust comment for drm_sched_tdr_queue_imm (Luben)
v4:
 - Adjust commit message (Luben)

Cc: Luben Tuikov 
Signed-off-by: Matthew Brost 
Reviewed-by: Luben Tuikov 
Link: https://lore.kernel.org/r/20231031032439.1558703-6-matthew.brost@intel.com
Signed-off-by: Luben Tuikov

drm/sched: Split free_job into own work item

2023-11-01T21:29:21+00:00

Rather than call free_job and run_job in same work item have a dedicated
work item for each. This aligns with the design and intended use of work
queues.

v2:
   - Test for DMA_FENCE_FLAG_TIMESTAMP_BIT before setting
     timestamp in free_job() work item (Danilo)
v3:
  - Drop forward dec of drm_sched_select_entity (Boris)
  - Return in drm_sched_run_job_work if entity NULL (Boris)
v4:
  - Replace dequeue with peek and invert logic (Luben)
  - Wrap to 100 lines (Luben)
  - Update comments for *_queue / *_queue_if_ready functions (Luben)
v5:
  - Drop peek argument, blindly reinit idle (Luben)
  - s/drm_sched_free_job_queue_if_ready/drm_sched_free_job_queue_if_done (Luben)
  - Update work_run_job & work_free_job kernel doc (Luben)
v6:
  - Do not move drm_sched_select_entity in file (Luben)

Signed-off-by: Matthew Brost 
Link: https://lore.kernel.org/r/20231031032439.1558703-4-matthew.brost@intel.com
Reviewed-by: Luben Tuikov 
Signed-off-by: Luben Tuikov

drm/sched: Convert drm scheduler to use a work queue rather than kthread

2023-11-01T21:29:21+00:00

In Xe, the new Intel GPU driver, a choice has made to have a 1 to 1
mapping between a drm_gpu_scheduler and drm_sched_entity. At first this
seems a bit odd but let us explain the reasoning below.

1. In Xe the submission order from multiple drm_sched_entity is not
guaranteed to be the same completion even if targeting the same hardware
engine. This is because in Xe we have a firmware scheduler, the GuC,
which allowed to reorder, timeslice, and preempt submissions. If a using
shared drm_gpu_scheduler across multiple drm_sched_entity, the TDR falls
apart as the TDR expects submission order == completion order. Using a
dedicated drm_gpu_scheduler per drm_sched_entity solve this problem.

2. In Xe submissions are done via programming a ring buffer (circular
buffer), a drm_gpu_scheduler provides a limit on number of jobs, if the
limit of number jobs is set to RING_SIZE / MAX_SIZE_PER_JOB we get flow
control on the ring for free.

A problem with this design is currently a drm_gpu_scheduler uses a
kthread for submission / job cleanup. This doesn't scale if a large
number of drm_gpu_scheduler are used. To work around the scaling issue,
use a worker rather than kthread for submission / job cleanup.

v2:
  - (Rob Clark) Fix msm build
  - Pass in run work queue
v3:
  - (Boris) don't have loop in worker
v4:
  - (Tvrtko) break out submit ready, stop, start helpers into own patch
v5:
  - (Boris) default to ordered work queue
v6:
  - (Luben / checkpatch) fix alignment in msm_ringbuffer.c
  - (Luben) s/drm_sched_submit_queue/drm_sched_wqueue_enqueue
  - (Luben) Update comment for drm_sched_wqueue_enqueue
  - (Luben) Positive check for submit_wq in drm_sched_init
  - (Luben) s/alloc_submit_wq/own_submit_wq
v7:
  - (Luben) s/drm_sched_wqueue_enqueue/drm_sched_run_job_queue
v8:
  - (Luben) Adjust var names / comments

Signed-off-by: Matthew Brost 
Reviewed-by: Luben Tuikov 
Link: https://lore.kernel.org/r/20231031032439.1558703-3-matthew.brost@intel.com
Signed-off-by: Luben Tuikov

drm/sched: Add drm_sched_wqueue_* helpers

2023-11-01T21:29:20+00:00

Add scheduler wqueue ready, stop, and start helpers to hide the
implementation details of the scheduler from the drivers.

v2:
  - s/sched_wqueue/sched_wqueue (Luben)
  - Remove the extra white line after the return-statement (Luben)
  - update drm_sched_wqueue_ready comment (Luben)

Cc: Luben Tuikov 
Signed-off-by: Matthew Brost 
Reviewed-by: Luben Tuikov 
Link: https://lore.kernel.org/r/20231031032439.1558703-2-matthew.brost@intel.com
Signed-off-by: Luben Tuikov