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.
Signed-off-by: Matthew Brost <matthew.br...@intel.com>
---
drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c | 14 +--
drivers/gpu/drm/amd/amdgpu/amdgpu_device.c | 12 +-
drivers/gpu/drm/scheduler/sched_main.c | 124 ++++++++++++--------
include/drm/gpu_scheduler.h | 13 +-
4 files changed, 93 insertions(+), 70 deletions(-)
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
index f60753f97ac5..9c2a10aeb0b3 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_debugfs.c
@@ -1489,9 +1489,9 @@ static int amdgpu_debugfs_test_ib_show(struct seq_file
*m, void *unused)
for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
struct amdgpu_ring *ring = adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
- kthread_park(ring->sched.thread);
+ drm_sched_run_wq_stop(&ring->sched);
}
seq_printf(m, "run ib test:\n");
@@ -1505,9 +1505,9 @@ static int amdgpu_debugfs_test_ib_show(struct seq_file
*m, void *unused)
for (i = 0; i < AMDGPU_MAX_RINGS; i++) {
struct amdgpu_ring *ring = adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
- kthread_unpark(ring->sched.thread);
+ drm_sched_run_wq_start(&ring->sched);
}
up_write(&adev->reset_domain->sem);
@@ -1727,7 +1727,7 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
ring = adev->rings[val];
- if (!ring || !ring->funcs->preempt_ib || !ring->sched.thread)
+ if (!ring || !ring->funcs->preempt_ib || !ring->sched.ready)
return -EINVAL;
/* the last preemption failed */
@@ -1745,7 +1745,7 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
goto pro_end;
/* stop the scheduler */
- kthread_park(ring->sched.thread);
+ drm_sched_run_wq_stop(&ring->sched);
/* preempt the IB */
r = amdgpu_ring_preempt_ib(ring);
@@ -1779,7 +1779,7 @@ static int amdgpu_debugfs_ib_preempt(void *data, u64 val)
failure:
/* restart the scheduler */
- kthread_unpark(ring->sched.thread);
+ drm_sched_run_wq_start(&ring->sched);
up_read(&adev->reset_domain->sem);
diff --git a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
index 076ae400d099..9552929ccf87 100644
--- a/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
+++ b/drivers/gpu/drm/amd/amdgpu/amdgpu_device.c
@@ -4577,7 +4577,7 @@ bool amdgpu_device_has_job_running(struct amdgpu_device
*adev)
for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
struct amdgpu_ring *ring = adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
spin_lock(&ring->sched.job_list_lock);
@@ -4708,7 +4708,7 @@ int amdgpu_device_pre_asic_reset(struct amdgpu_device
*adev,
for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
struct amdgpu_ring *ring = adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
/*clear job fence from fence drv to avoid force_completion
@@ -5247,7 +5247,7 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev,
for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
struct amdgpu_ring *ring = tmp_adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
drm_sched_stop(&ring->sched, job ? &job->base : NULL);
@@ -5321,7 +5321,7 @@ int amdgpu_device_gpu_recover(struct amdgpu_device *adev,
for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
struct amdgpu_ring *ring = tmp_adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
drm_sched_start(&ring->sched, true);
@@ -5648,7 +5648,7 @@ pci_ers_result_t amdgpu_pci_error_detected(struct pci_dev
*pdev, pci_channel_sta
for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
struct amdgpu_ring *ring = adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
drm_sched_stop(&ring->sched, NULL);
@@ -5776,7 +5776,7 @@ void amdgpu_pci_resume(struct pci_dev *pdev)
for (i = 0; i < AMDGPU_MAX_RINGS; ++i) {
struct amdgpu_ring *ring = adev->rings[i];
- if (!ring || !ring->sched.thread)
+ if (!ring || !ring->sched.ready)
continue;
drm_sched_start(&ring->sched, true);
diff --git a/drivers/gpu/drm/scheduler/sched_main.c
b/drivers/gpu/drm/scheduler/sched_main.c
index 27d52ffbb808..8c64045d0692 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -44,7 +44,6 @@
* The jobs in a entity are always scheduled in the order that they were
pushed.
*/
-#include <linux/kthread.h>
#include <linux/wait.h>
#include <linux/sched.h>
#include <linux/completion.h>
@@ -251,6 +250,53 @@ drm_sched_rq_select_entity_fifo(struct drm_sched_rq *rq)
return rb ? rb_entry(rb, struct drm_sched_entity, rb_tree_node) : NULL;
}
+/**
+ * drm_sched_run_wq_stop - stop scheduler run worker
+ *
+ * @sched: scheduler instance to stop run worker
+ */
+void drm_sched_run_wq_stop(struct drm_gpu_scheduler *sched)
+{
+ sched->pause_run_wq = true;
+ smp_wmb();
+
+ cancel_work_sync(&sched->work_run);
+}
+EXPORT_SYMBOL(drm_sched_run_wq_stop);
+
+/**
+ * drm_sched_run_wq_start - start scheduler run worker
+ *
+ * @sched: scheduler instance to start run worker
+ */
+void drm_sched_run_wq_start(struct drm_gpu_scheduler *sched)
+{
+ sched->pause_run_wq = false;
+ smp_wmb();
+
+ queue_work(sched->run_wq, &sched->work_run);
+}
+EXPORT_SYMBOL(drm_sched_run_wq_start);
+
+/**
+ * drm_sched_run_wq_queue - queue scheduler run worker
+ *
+ * @sched: scheduler instance to queue run worker
+ */
+static void drm_sched_run_wq_queue(struct drm_gpu_scheduler *sched)
+{
+ smp_rmb();
+
+ /*
+ * Try not to schedule work if pause_run_wq set but not the end of world
+ * if we do as either it will be cancelled by the above
+ * cancel_work_sync, or drm_sched_main turns into a NOP while
+ * pause_run_wq is set.
+ */
+ if (!sched->pause_run_wq)
+ queue_work(sched->run_wq, &sched->work_run);
+}
+
/**
* drm_sched_job_done - complete a job
* @s_job: pointer to the job which is done
@@ -270,7 +316,7 @@ static void drm_sched_job_done(struct drm_sched_job *s_job)
dma_fence_get(&s_fence->finished);
drm_sched_fence_finished(s_fence);
dma_fence_put(&s_fence->finished);
- wake_up_interruptible(&sched->wake_up_worker);
+ drm_sched_run_wq_queue(sched);
}
/**
@@ -433,7 +479,7 @@ void drm_sched_stop(struct drm_gpu_scheduler *sched, struct
drm_sched_job *bad)
{
struct drm_sched_job *s_job, *tmp;
- kthread_park(sched->thread);
+ drm_sched_run_wq_stop(sched);
/*
* Reinsert back the bad job here - now it's safe as
@@ -546,7 +592,7 @@ void drm_sched_start(struct drm_gpu_scheduler *sched, bool
full_recovery)
spin_unlock(&sched->job_list_lock);
}
- kthread_unpark(sched->thread);
+ drm_sched_run_wq_start(sched);
}
EXPORT_SYMBOL(drm_sched_start);
@@ -831,7 +877,7 @@ static bool drm_sched_ready(struct drm_gpu_scheduler *sched)
void drm_sched_wakeup(struct drm_gpu_scheduler *sched)
{
if (drm_sched_ready(sched))
- wake_up_interruptible(&sched->wake_up_worker);
+ drm_sched_run_wq_queue(sched);
}
/**
@@ -941,60 +987,42 @@ drm_sched_pick_best(struct drm_gpu_scheduler **sched_list,
}
EXPORT_SYMBOL(drm_sched_pick_best);
-/**
- * drm_sched_blocked - check if the scheduler is blocked
- *
- * @sched: scheduler instance
- *
- * Returns true if blocked, otherwise false.
- */
-static bool drm_sched_blocked(struct drm_gpu_scheduler *sched)
-{
- if (kthread_should_park()) {
- kthread_parkme();
- return true;
- }
-
- return false;
-}
-
/**
* drm_sched_main - main scheduler thread
*
* @param: scheduler instance
- *
- * Returns 0.
*/
-static int drm_sched_main(void *param)
+static void drm_sched_main(struct work_struct *w)
{
- struct drm_gpu_scheduler *sched = (struct drm_gpu_scheduler *)param;
+ struct drm_gpu_scheduler *sched =
+ container_of(w, struct drm_gpu_scheduler, work_run);
int r;
- sched_set_fifo_low(current);
-
- while (!kthread_should_stop()) {
- struct drm_sched_entity *entity = NULL;
+ while (!READ_ONCE(sched->pause_run_wq)) {
+ struct drm_sched_entity *entity;
struct drm_sched_fence *s_fence;
struct drm_sched_job *sched_job;
struct dma_fence *fence;
- struct drm_sched_job *cleanup_job = NULL;
+ struct drm_sched_job *cleanup_job;
- wait_event_interruptible(sched->wake_up_worker,
- (cleanup_job =
drm_sched_get_cleanup_job(sched)) ||
- (!drm_sched_blocked(sched) &&
- (entity =
drm_sched_select_entity(sched))) ||
- kthread_should_stop());
+ cleanup_job = drm_sched_get_cleanup_job(sched);
+ entity = drm_sched_select_entity(sched);
if (cleanup_job)
sched->ops->free_job(cleanup_job);
- if (!entity)
+ if (!entity) {
+ if (!cleanup_job)
+ break;
continue;
+ }
sched_job = drm_sched_entity_pop_job(entity);
if (!sched_job) {
complete_all(&entity->entity_idle);
+ if (!cleanup_job)
+ break;
continue;
}
@@ -1022,14 +1050,14 @@ static int drm_sched_main(void *param)
r);
} else {
if (IS_ERR(fence))
- dma_fence_set_error(&s_fence->finished,
PTR_ERR(fence));
+ dma_fence_set_error(&s_fence->finished,
+ PTR_ERR(fence));
drm_sched_job_done(sched_job);
}
wake_up(&sched->job_scheduled);
}
- return 0;
}
/**
@@ -1054,35 +1082,28 @@ int drm_sched_init(struct drm_gpu_scheduler *sched,
long timeout, struct workqueue_struct *timeout_wq,
atomic_t *score, const char *name, struct device *dev)
{
- int i, ret;
+ int i;
sched->ops = ops;
sched->hw_submission_limit = hw_submission;
sched->name = name;
sched->timeout = timeout;
sched->timeout_wq = timeout_wq ? : system_wq;
+ sched->run_wq = system_wq; /* FIXME: Let user pass this in */
sched->hang_limit = hang_limit;
sched->score = score ? score : &sched->_score;
sched->dev = dev;
for (i = DRM_SCHED_PRIORITY_MIN; i < DRM_SCHED_PRIORITY_COUNT; i++)
drm_sched_rq_init(sched, &sched->sched_rq[i]);
- init_waitqueue_head(&sched->wake_up_worker);
init_waitqueue_head(&sched->job_scheduled);
INIT_LIST_HEAD(&sched->pending_list);
spin_lock_init(&sched->job_list_lock);
atomic_set(&sched->hw_rq_count, 0);
INIT_DELAYED_WORK(&sched->work_tdr, drm_sched_job_timedout);
+ INIT_WORK(&sched->work_run, drm_sched_main);
atomic_set(&sched->_score, 0);
atomic64_set(&sched->job_id_count, 0);
-
- /* Each scheduler will run on a seperate kernel thread */
- sched->thread = kthread_run(drm_sched_main, sched, sched->name);
- if (IS_ERR(sched->thread)) {
- ret = PTR_ERR(sched->thread);
- sched->thread = NULL;
- DRM_DEV_ERROR(sched->dev, "Failed to create scheduler for
%s.\n", name);
- return ret;
- }
+ sched->pause_run_wq = false;
sched->ready = true;
return 0;
@@ -1101,8 +1122,7 @@ void drm_sched_fini(struct drm_gpu_scheduler *sched)
struct drm_sched_entity *s_entity;
int i;
- if (sched->thread)
- kthread_stop(sched->thread);
+ drm_sched_run_wq_stop(sched);
for (i = DRM_SCHED_PRIORITY_COUNT - 1; i >= DRM_SCHED_PRIORITY_MIN;
i--) {
struct drm_sched_rq *rq = &sched->sched_rq[i];
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index ca857ec9e7eb..ff50f3c289cd 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -456,17 +456,16 @@ struct drm_sched_backend_ops {
* @timeout: the time after which a job is removed from the scheduler.
* @name: name of the ring for which this scheduler is being used.
* @sched_rq: priority wise array of run queues.
- * @wake_up_worker: the wait queue on which the scheduler sleeps until a job
- * is ready to be scheduled.
* @job_scheduled: once @drm_sched_entity_do_release is called the scheduler
* waits on this wait queue until all the scheduled jobs are
* finished.
* @hw_rq_count: the number of jobs currently in the hardware queue.
* @job_id_count: used to assign unique id to the each job.
+ * @run_wq: workqueue used to queue @work_run
* @timeout_wq: workqueue used to queue @work_tdr
+ * @work_run: schedules jobs and cleans up entities
* @work_tdr: schedules a delayed call to @drm_sched_job_timedout after the
* timeout interval is over.
- * @thread: the kthread on which the scheduler which run.
* @pending_list: the list of jobs which are currently in the job queue.
* @job_list_lock: lock to protect the pending_list.
* @hang_limit: once the hangs by a job crosses this limit then it is marked
@@ -475,6 +474,7 @@ struct drm_sched_backend_ops {
* @_score: score used when the driver doesn't provide one
* @ready: marks if the underlying HW is ready to work
* @free_guilty: A hit to time out handler to free the guilty job.
+ * @pause_run_wq: pause queuing of @work_run on @run_wq
* @dev: system &struct device
*
* One scheduler is implemented for each hardware ring.
@@ -485,13 +485,13 @@ struct drm_gpu_scheduler {
long timeout;
const char *name;
struct drm_sched_rq sched_rq[DRM_SCHED_PRIORITY_COUNT];
- wait_queue_head_t wake_up_worker;
wait_queue_head_t job_scheduled;
atomic_t hw_rq_count;
atomic64_t job_id_count;
+ struct workqueue_struct *run_wq;
struct workqueue_struct *timeout_wq;
+ struct work_struct work_run;
struct delayed_work work_tdr;
- struct task_struct *thread;
struct list_head pending_list;
spinlock_t job_list_lock;
int hang_limit;
@@ -499,6 +499,7 @@ struct drm_gpu_scheduler {
atomic_t _score;
bool ready;
bool free_guilty;
+ bool pause_run_wq;
struct device *dev;
};
@@ -529,6 +530,8 @@ void drm_sched_entity_modify_sched(struct drm_sched_entity
*entity,
void drm_sched_job_cleanup(struct drm_sched_job *job);
void drm_sched_wakeup(struct drm_gpu_scheduler *sched);
+void drm_sched_run_wq_stop(struct drm_gpu_scheduler *sched);
+void drm_sched_run_wq_start(struct drm_gpu_scheduler *sched);
void drm_sched_stop(struct drm_gpu_scheduler *sched, struct drm_sched_job
*bad);
void drm_sched_start(struct drm_gpu_scheduler *sched, bool full_recovery);
void drm_sched_resubmit_jobs(struct drm_gpu_scheduler *sched);
--
2.37.3
