Am 12.01.20 um 02:25 schrieb Nirmoy Das:
This patch adds required fields to drm_sched_job and drm_gpu_scheduler
structure to cumulatively calculate amount of time a drm_gpu_scheduler
spend on serving a job.
Using least used drm scheduler to choose a run queue
improves drm_sched_entity_get_free_sched()'s job distribution
Below are test results after running amdgpu_test from mesa drm
Before this patch:
sched_name num of many times it got scheduled
========= ==================================
sdma0 314
sdma1 32
comp_1.0.0 56
After this patch:
sched_name num of many times it got scheduled
========= ==================================
sdma0 113
sdma1 383
comp_1.0.0 9
comp_1.0.1 9
comp_1.1.0 8
comp_1.1.1 8
comp_1.2.0 12
comp_1.2.1 13
comp_1.3.0 16
comp_1.3.1 9
Signed-off-by: Nirmoy Das <nirmoy.das@xxxxxxx>
Well that is a nice start, but a couple of comments below.
---
drivers/gpu/drm/scheduler/sched_entity.c | 9 +++++----
drivers/gpu/drm/scheduler/sched_main.c | 2 ++
include/drm/gpu_scheduler.h | 2 ++
3 files changed, 9 insertions(+), 4 deletions(-)
diff --git a/drivers/gpu/drm/scheduler/sched_entity.c b/drivers/gpu/drm/scheduler/sched_entity.c
index 2e3a058fc239..b5555af787d0 100644
--- a/drivers/gpu/drm/scheduler/sched_entity.c
+++ b/drivers/gpu/drm/scheduler/sched_entity.c
@@ -130,7 +130,7 @@ static struct drm_sched_rq *
drm_sched_entity_get_free_sched(struct drm_sched_entity *entity)
{
struct drm_sched_rq *rq = NULL;
- unsigned int min_jobs = UINT_MAX, num_jobs;
+ uint64_t min_time_consumed = -1, total_consumed_time;
int i;
for (i = 0; i < entity->num_sched_list; ++i) {
@@ -141,9 +141,9 @@ drm_sched_entity_get_free_sched(struct drm_sched_entity *entity)
continue;
}
- num_jobs = atomic_read(&sched->num_jobs);
- if (num_jobs < min_jobs) {
- min_jobs = num_jobs;
+ total_consumed_time = sched->total_consumed_time;
+ if (total_consumed_time < min_time_consumed) {
+ min_time_consumed = total_consumed_time;
rq = &entity->sched_list[i]->sched_rq[entity->priority];
You might want to remove num_jobs now completely since it unused, but
consider the whole algorithm first. See below for that.
}
}
@@ -499,6 +499,7 @@ void drm_sched_entity_push_job(struct drm_sched_job *sched_job,
trace_drm_sched_job(sched_job, entity);
atomic_inc(&entity->rq->sched->num_jobs);
+ sched_job->start_time = ktime_get_ns();
WRITE_ONCE(entity->last_user, current->group_leader);
first = spsc_queue_push(&entity->job_queue, &sched_job->queue_node);
diff --git a/drivers/gpu/drm/scheduler/sched_main.c b/drivers/gpu/drm/scheduler/sched_main.c
index 3fad5876a13f..67fdf4f248d4 100644
--- a/drivers/gpu/drm/scheduler/sched_main.c
+++ b/drivers/gpu/drm/scheduler/sched_main.c
@@ -653,6 +653,7 @@ static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
struct drm_sched_job *s_job = container_of(cb, struct drm_sched_job, cb);
struct drm_sched_fence *s_fence = s_job->s_fence;
struct drm_gpu_scheduler *sched = s_fence->sched;
+ uint64_t end = ktime_get_ns();
atomic_dec(&sched->hw_rq_count);
atomic_dec(&sched->num_jobs);
@@ -660,6 +661,7 @@ static void drm_sched_process_job(struct dma_fence *f, struct dma_fence_cb *cb)
trace_drm_sched_process_job(s_fence);
drm_sched_fence_finished(s_fence);
+ s_job->sched->total_consumed_time += end - s_job->start_time;
Don't use s_job->sched here, use the local variable sched (s_job might
already be destroyed).
The next problem is that you somehow need to protect total_consumed_time
from concurrent updates, a 64bit atomic should probably do it.
Another problem from the algorithm point of view is that the
total_time_consumed of each scheduler doesn't necessary say anything
about a good scheduling decision for the future.
For example there could have been a lot of work from a single queue to
SDMA0 in the past, but now both SDMA0 and SDMA1 are idle.
Scheduling everything to SDMA1 until we catch up with SDMA0 is certainly
not a good idea. Since this counters the whole idea of load balancing.
Regards,
Christian.
wake_up_interruptible(&sched->wake_up_worker);
}
diff --git a/include/drm/gpu_scheduler.h b/include/drm/gpu_scheduler.h
index 96a1a1b7526e..496d9b209d12 100644
--- a/include/drm/gpu_scheduler.h
+++ b/include/drm/gpu_scheduler.h
@@ -191,6 +191,7 @@ struct drm_sched_job {
struct dma_fence_cb finish_cb;
struct list_head node;
uint64_t id;
+ uint64_t start_time;
atomic_t karma;
enum drm_sched_priority s_priority;
struct drm_sched_entity *entity;
@@ -285,6 +286,7 @@ struct drm_gpu_scheduler {
atomic_t num_jobs;
bool ready;
bool free_guilty;
+ uint64_t total_consumed_time;
};
int drm_sched_init(struct drm_gpu_scheduler *sched,
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