[PATCH v2 5/9] drm/xe: Add dependency scheduler for GT TLB invalidations to bind queues

[Summers, Stuart]

On Wed, 2025-07-02 at 16:42 -0700, Matthew Brost wrote:
> Add a generic dependency scheduler for GT TLB invalidations, used to
> schedule jobs that issue GT TLB invalidations to bind queues.
> 
> v2:
>  - Use shared GT TLB invalidation queue for dep scheduler
>  - Break allocation of dep scheduler into its own function
>  - Add define for max number tlb invalidations
>  - Skip media if not present
> 
> Suggested-by: Thomas Hellström <thomas.hellstrom at linux.intel.com>
> Signed-off-by: Matthew Brost <matthew.brost at intel.com>
> ---
>  drivers/gpu/drm/xe/xe_exec_queue.c       | 48
> ++++++++++++++++++++++++
>  drivers/gpu/drm/xe/xe_exec_queue_types.h | 13 +++++++
>  2 files changed, 61 insertions(+)
> 
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue.c
> b/drivers/gpu/drm/xe/xe_exec_queue.c
> index fee22358cc09..7aaf669cf5fc 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue.c
> +++ b/drivers/gpu/drm/xe/xe_exec_queue.c
> @@ -12,6 +12,7 @@
>  #include <drm/drm_file.h>
>  #include <uapi/drm/xe_drm.h>
>  
> +#include "xe_dep_scheduler.h"
>  #include "xe_device.h"
>  #include "xe_gt.h"
>  #include "xe_hw_engine_class_sysfs.h"
> @@ -39,6 +40,12 @@ static int exec_queue_user_extensions(struct
> xe_device *xe, struct xe_exec_queue
>  
>  static void __xe_exec_queue_free(struct xe_exec_queue *q)
>  {
> +       int i;
> +
> +       for (i = 0; i < XE_EXEC_QUEUE_TLB_INVAL_COUNT; ++i)
> +               if (q->tlb_inval[i].dep_scheduler)
> +                       xe_dep_scheduler_fini(q-
> >tlb_inval[i].dep_scheduler);
> +
>         if (xe_exec_queue_uses_pxp(q))
>                 xe_pxp_exec_queue_remove(gt_to_xe(q->gt)->pxp, q);
>         if (q->vm)
> @@ -50,6 +57,39 @@ static void __xe_exec_queue_free(struct
> xe_exec_queue *q)
>         kfree(q);
>  }
>  
> +static int alloc_dep_schedulers(struct xe_device *xe, struct
> xe_exec_queue *q)
> +{
> +       struct xe_tile *tile = gt_to_tile(q->gt);
> +       int i;
> +
> +       for (i = 0; i < XE_EXEC_QUEUE_TLB_INVAL_COUNT; ++i) {
> +               struct xe_dep_scheduler *dep_scheduler;
> +               struct xe_gt *gt;
> +               struct workqueue_struct *wq;
> +
> +               if (i == XE_EXEC_QUEUE_TLB_INVAL_PRIMARY_GT)
> +                       gt = tile->primary_gt;
> +               else
> +                       gt = tile->media_gt;
> +
> +               if (!gt)
> +                       continue;
> +
> +               wq = gt->tlb_invalidation.job_wq;
> +
> +#define MAX_TLB_INVAL_JOBS     16      /* Picking a reasonable value
> */

So if we exceed tihs number, that means we won't get an invalidation of
that range before a context switch to a new queue?

> +               dep_scheduler = xe_dep_scheduler_create(xe, wq, q-
> >name,
> +                                                       MAX_TLB_INVAL
> _JOBS);
> +               if (IS_ERR(dep_scheduler))
> +                       return PTR_ERR(dep_scheduler);
> +
> +               q->tlb_inval[i].dep_scheduler = dep_scheduler;
> +       }
> +#undef MAX_TLB_INVAL_JOBS
> +
> +       return 0;
> +}
> +
>  static struct xe_exec_queue *__xe_exec_queue_alloc(struct xe_device
> *xe,
>                                                    struct xe_vm *vm,
>                                                    u32 logical_mask,
> @@ -94,6 +134,14 @@ static struct xe_exec_queue
> *__xe_exec_queue_alloc(struct xe_device *xe,
>         else
>                 q->sched_props.priority =
> XE_EXEC_QUEUE_PRIORITY_NORMAL;

We want these to be high priority right? I.e. if another user creates a
queue and submits at high priority can we get stale data on those
executions if this one is blocked behind that high priority one?

Thanks,
Stuart

>  
> +       if (q->flags & (EXEC_QUEUE_FLAG_MIGRATE |
> EXEC_QUEUE_FLAG_VM)) {
> +               err = alloc_dep_schedulers(xe, q);
> +               if (err) {
> +                       __xe_exec_queue_free(q);
> +                       return ERR_PTR(err);
> +               }
> +       }
> +
>         if (vm)
>                 q->vm = xe_vm_get(vm);
>  
> diff --git a/drivers/gpu/drm/xe/xe_exec_queue_types.h
> b/drivers/gpu/drm/xe/xe_exec_queue_types.h
> index abdf4a57e6e2..ba443a497b38 100644
> --- a/drivers/gpu/drm/xe/xe_exec_queue_types.h
> +++ b/drivers/gpu/drm/xe/xe_exec_queue_types.h
> @@ -134,6 +134,19 @@ struct xe_exec_queue {
>                 struct list_head link;
>         } lr;
>  
> +#define XE_EXEC_QUEUE_TLB_INVAL_PRIMARY_GT     0
> +#define XE_EXEC_QUEUE_TLB_INVAL_MEDIA_GT       1
> +#define
> XE_EXEC_QUEUE_TLB_INVAL_COUNT          (XE_EXEC_QUEUE_TLB_INVAL_MEDIA
> _GT  + 1)
> +
> +       /** @tlb_inval: TLB invalidations exec queue state */
> +       struct {
> +               /**
> +                * @tlb_inval.dep_scheduler: The TLB invalidation
> +                * dependency scheduler
> +                */
> +               struct xe_dep_scheduler *dep_scheduler;
> +       } tlb_inval[XE_EXEC_QUEUE_TLB_INVAL_COUNT];
> +
>         /** @pxp: PXP info tracking */
>         struct {
>                 /** @pxp.type: PXP session type used by this queue */