Re: [PATCH] drm/xe: Don't restart parallel queues multiple times on GT reset

[Nirmoy Das <nirmoy.das@intel.com>]

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On 10/22/2024 1:02 AM, Matthew Brost wrote:
> On Mon, Oct 21, 2024 at 11:11:46PM +0200, Nirmoy Das wrote:
>> In case of parallel submissions multiple GuC id will point to the
>> same exec queue and on GT reset such exec queues will get restarted
>> multiple times which is not desirable.
>>
>> Link: https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2295
>> Cc: Himal Prasad Ghimiray <himal.prasad.ghimiray@intel.com>
>> Cc: Matthew Auld <matthew.auld@intel.com>
>> Cc: Matthew Brost <matthew.brost@intel.com>
>> Cc: Tejas Upadhyay <tejas.upadhyay@intel.com>
>> Signed-off-by: Nirmoy Das <nirmoy.das@intel.com>
>> ---
>>  drivers/gpu/drm/xe/xe_guc_submit.c | 7 ++++++-
>>  1 file changed, 6 insertions(+), 1 deletion(-)
>>
>> diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c b/drivers/gpu/drm/xe/xe_guc_submit.c
>> index 0b81972ff651..6aeb007eaf06 100644
>> --- a/drivers/gpu/drm/xe/xe_guc_submit.c
>> +++ b/drivers/gpu/drm/xe/xe_guc_submit.c
>> @@ -1784,8 +1784,13 @@ int xe_guc_submit_start(struct xe_guc *guc)
>>  
>>  	mutex_lock(&guc->submission_state.lock);
>>  	atomic_dec(&guc->submission_state.stopped);
>> -	xa_for_each(&guc->submission_state.exec_queue_lookup, index, q)
>> +	xa_for_each(&guc->submission_state.exec_queue_lookup, index, q) {
>> +		/* Skip restarting parallel queues */
>> +		if (exec_queue_enabled(q) && xe_exec_queue_is_parallel(q))
>> +			continue;
> This doesn't look right as exec_queue_enabled can race here...

Ah right, just realized this happens async with the run_job


>
> I think this should be...
>
> if (q->guc->id != index)
> 	continue;


This looks much better. I will try it out and resend.


>
> This way we only call guc_exec_queue_start once per queue parallel exec
> queue. Also I think we need to add the same check to xe_guc_submit_stop.


I will resend with updated xe_guc_submit_stop()

thanks,

Nirmoy

> Matt
>
>> +
>>  		guc_exec_queue_start(q);
>> +	}
>>  	mutex_unlock(&guc->submission_state.lock);
>>  
>>  	wake_up_all(&guc->ct.wq);
>> -- 
>> 2.46.0
>>

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