Re: drm/xe: Document exec queue priority rules

[Daniel Charles <daniel.charles@intel.com>]

On 2/23/2026 1:24 PM, Stuart Summers wrote:
> Add some documentation around how the GuC will employ
> the xe_exec_queue priorities provided by userspace
> application.
>
> Signed-off-by: Stuart Summers <stuart.summers@intel.com>
> ---
>   drivers/gpu/drm/xe/xe_exec_queue_types.h | 24 ++++++++++++++++++++++++
>   1 file changed, 24 insertions(+)
>
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue_types.h b/drivers/gpu/drm/xe/xe_exec_queue_types.h
> index 3791fed34ffa..aefebfc6996e 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue_types.h
> +++ b/drivers/gpu/drm/xe/xe_exec_queue_types.h
> @@ -22,6 +22,30 @@ struct xe_guc_exec_queue;
>   struct xe_hw_engine;
>   struct xe_vm;
>   
> +/**
> + * enum xe_exec_queue_priority - Exec Queue priority values
> + *
> + * XeKMD uses GuC as the primary submission vehicle to HW.
> + * GuC has 4 priority levels that roughly map to the 4 levels
> + * shown here but in reverse order. GuC scheduler uses time
> + * slicing to determine how long a queue should remain on the
> + * command streamer before issuing a preemption request to
> + * allow execution of another queue.
> + *
> + * The following rules should be considered by applications
> + * employing these queue priorities:
> + *  - A HIGH priority request will preempt a NORMAL and LOW
> + *    priority request when submitted and based on the time
> + *    slice quantum.
> + *  - A NORMAL priority request will preempt a LOW priority
> + *    request when submitted and based on that time slice
> + *    quantum but will not preempt a HIGH priority request
> + *    until that time slice quantum has been reached.
> + *  - A LOW priority request will never preempt either a
> + *    MEDIUM or HIGH priority context.
> + *  - Currently KERNEL level priority is reserved, as the name
> + *    suggests, for kernel-submitted queues only.
> + */

This looks good to me

Reviewed-by: Daniel Charles <daniel.charles@intel.com>

>   enum xe_exec_queue_priority {
>   	XE_EXEC_QUEUE_PRIORITY_UNSET = -2, /* For execlist usage only */
>   	XE_EXEC_QUEUE_PRIORITY_LOW = 0,