Re: [PATCH] drm/xe: Use ordered WQ for G2H handler

[Francois Dugast <francois.dugast@intel.com>]

On Sun, May 05, 2024 at 08:47:58PM -0700, Matthew Brost wrote:
> System work queues are shared, use a dedicated work queue for G2H
> processing to avoid G2H processing getting block behind system tasks.
> 
> Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
> Cc: <stable@vger.kernel.org>
> Signed-off-by: Matthew Brost <matthew.brost@intel.com>

Reviewed-by: Francois Dugast <francois.dugast@intel.com>

> ---
>  drivers/gpu/drm/xe/xe_guc_ct.c       | 5 +++++
>  drivers/gpu/drm/xe/xe_guc_ct.h       | 2 +-
>  drivers/gpu/drm/xe/xe_guc_ct_types.h | 2 ++
>  3 files changed, 8 insertions(+), 1 deletion(-)
> 
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.c b/drivers/gpu/drm/xe/xe_guc_ct.c
> index 8ac819a7061e..cc60c3333ce3 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.c
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.c
> @@ -121,6 +121,7 @@ static void guc_ct_fini(struct drm_device *drm, void *arg)
>  {
>  	struct xe_guc_ct *ct = arg;
>  
> +	destroy_workqueue(ct->g2h_wq);
>  	xa_destroy(&ct->fence_lookup);
>  }
>  
> @@ -146,6 +147,10 @@ int xe_guc_ct_init(struct xe_guc_ct *ct)
>  
>  	xe_gt_assert(gt, !(guc_ct_size() % PAGE_SIZE));
>  
> +	ct->g2h_wq = alloc_ordered_workqueue("xe-g2h-wq", 0);
> +	if(!ct->g2h_wq)
> +		return -ENOMEM;
> +
>  	spin_lock_init(&ct->fast_lock);
>  	xa_init(&ct->fence_lookup);
>  	INIT_WORK(&ct->g2h_worker, g2h_worker_func);
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct.h b/drivers/gpu/drm/xe/xe_guc_ct.h
> index 5083e099064f..105bb8e99a8d 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct.h
> +++ b/drivers/gpu/drm/xe/xe_guc_ct.h
> @@ -34,7 +34,7 @@ static inline void xe_guc_ct_irq_handler(struct xe_guc_ct *ct)
>  		return;
>  
>  	wake_up_all(&ct->wq);
> -	queue_work(system_unbound_wq, &ct->g2h_worker);
> +	queue_work(ct->g2h_wq, &ct->g2h_worker);
>  	xe_guc_ct_fast_path(ct);
>  }
>  
> diff --git a/drivers/gpu/drm/xe/xe_guc_ct_types.h b/drivers/gpu/drm/xe/xe_guc_ct_types.h
> index d29144c9f20b..fede4c6e93cb 100644
> --- a/drivers/gpu/drm/xe/xe_guc_ct_types.h
> +++ b/drivers/gpu/drm/xe/xe_guc_ct_types.h
> @@ -120,6 +120,8 @@ struct xe_guc_ct {
>  	wait_queue_head_t wq;
>  	/** @g2h_fence_wq: wait queue used for G2H fencing */
>  	wait_queue_head_t g2h_fence_wq;
> +	/** @g2h_wq: used to process G2H */
> +	struct workqueue_struct *g2h_wq;
>  	/** @msg: Message buffer */
>  	u32 msg[GUC_CTB_MSG_MAX_LEN];
>  	/** @fast_msg: Message buffer */
> -- 
> 2.34.1
>