Since switching the scheduler from using kthreads to workqueues in
commit a6149f039369 ("drm/sched: Convert drm scheduler to use a work
queue rather than kthread") userspace applications cannot determine
the device from the PID of the threads sending the trace events
anymore.

Each queue had its own kthread which had a given PID for the whole
time. So, at least for amdgpu, it was possible to associate a PID
to the hardware queues of each GPU in the system. Then, when a
drm_run_job trace event was received by userspace, the source PID
allowed to associate it back to the correct GPU.

With workqueues this is not possible anymore, so the event needs to
contain the dev_name() to identify the device.

Reviewed-by: Christian König <christian.koenig@amd.com>
Signed-off-by: Pierre-Eric Pelloux-Prayer <pierre-eric.pelloux-prayer@amd.com>
---
 drivers/gpu/drm/scheduler/gpu_scheduler_trace.h | 6 ++++--
 1 file changed, 4 insertions(+), 2 deletions(-)

diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
index f56e77e7f6d0..713df3516a17 100644
--- a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
+++ b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
@@ -42,6 +42,7 @@ DECLARE_EVENT_CLASS(drm_sched_job,
 			     __field(uint64_t, id)
 			     __field(u32, job_count)
 			     __field(int, hw_job_count)
+			     __string(dev, dev_name(sched_job->sched->dev))
 			     ),
 
 	    TP_fast_assign(
@@ -52,9 +53,10 @@ DECLARE_EVENT_CLASS(drm_sched_job,
 			   __entry->job_count = spsc_queue_count(&entity->job_queue);
 			   __entry->hw_job_count = atomic_read(
 				   &sched_job->sched->credit_count);
+			   __assign_str(dev);
 			   ),
-	    TP_printk("entity=%p, id=%llu, fence=%p, ring=%s, job count:%u, hw job count:%d",
-		      __entry->entity, __entry->id,
+	    TP_printk("dev=%s, entity=%p, id=%llu, fence=%p, ring=%s, job count:%u, hw job count:%d",
+		      __get_str(dev), __entry->entity, __entry->id,
 		      __entry->fence, __get_str(name),
 		      __entry->job_count, __entry->hw_job_count)
 );
-- 
2.43.0

On Thu, Apr 24, 2025 at 10:38:15AM +0200, Pierre-Eric Pelloux-Prayer wrote:
> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
> index f56e77e7f6d0..713df3516a17 100644
> --- a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
> @@ -42,6 +42,7 @@ DECLARE_EVENT_CLASS(drm_sched_job,
>  			     __field(uint64_t, id)
>  			     __field(u32, job_count)
>  			     __field(int, hw_job_count)
> +			     __string(dev, dev_name(sched_job->sched->dev))

Using the sched_job->sched pointer here and in other trace events implies that
the trace event must not be called before the sched_job->sched has been set,
i.e. in drm_sched_job_arm().

Please document this for the corresponding trace events.

Le 19/05/2025 à 17:34, Danilo Krummrich a écrit :
> On Thu, Apr 24, 2025 at 10:38:15AM +0200, Pierre-Eric Pelloux-Prayer wrote:
>> diff --git a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
>> index f56e77e7f6d0..713df3516a17 100644
>> --- a/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
>> +++ b/drivers/gpu/drm/scheduler/gpu_scheduler_trace.h
>> @@ -42,6 +42,7 @@ DECLARE_EVENT_CLASS(drm_sched_job,
>>   			     __field(uint64_t, id)
>>   			     __field(u32, job_count)
>>   			     __field(int, hw_job_count)
>> +			     __string(dev, dev_name(sched_job->sched->dev))
> 
> Using the sched_job->sched pointer here and in other trace events implies that
> the trace event must not be called before the sched_job->sched has been set,
> i.e. in drm_sched_job_arm().
> 
> Please document this for the corresponding trace events.

This is not a new requirement as sched and s_fence were already used by the trace events.

Still it's a good idea to document this, so I'll update the comment added in the documentation patch.

Thanks,
Pierre-Eric