Re: [RFC 4/8] drm/xe: Convert to per gt scheduler workers

[Tvrtko Ursulin]

On 03/07/2026 10:06, Matthew Brost wrote:
On Thu, Jul 02, 2026 at 03:37:41PM +0100, Tvrtko Ursulin wrote:
As the submission side of xe is serialized by the global GuC CT lock, we
can easily afford to create our own per gt work queues. Whereas before
kernel could create up to the number of CPUs threads, we now create one
per GT.


This breaks down for any execution queue that waits in a scheduler work
item for any reason. Long-running preemption queues do this for
time-slicing, multi-queue registration, and possibly a few other cases.

I've looked at this before and rough divide is this works for 3D but not
long running.

Hmmm curious. Could you expand a bit more on this?

Where do those wait, in run job or prepare job? And on what ie. where is 
the cross-dependency?

Is it related to the alien work items xe "injects" onto the scheduler 
workers?

Regards,

Tvrtko

Signed-off-by: Tvrtko Ursulin <tvrtko.ursu...@igalia.com>
Cc: Matthew Brost <matthew.br...@intel.com>
Cc: Rodrigo Vivi <rodrigo.v...@intel.com>
Cc: "Thomas Hellström" <thomas.hellst...@linux.intel.com>
---
  drivers/gpu/drm/xe/xe_gt.c         |  7 +++++++
  drivers/gpu/drm/xe/xe_gt_types.h   |  3 +++
  drivers/gpu/drm/xe/xe_guc_submit.c | 11 +++++++----
  3 files changed, 17 insertions(+), 4 deletions(-)

diff --git a/drivers/gpu/drm/xe/xe_gt.c b/drivers/gpu/drm/xe/xe_gt.c
index 783eb6d631b5..fb2db9eff341 100644
--- a/drivers/gpu/drm/xe/xe_gt.c
+++ b/drivers/gpu/drm/xe/xe_gt.c
@@ -706,6 +706,8 @@ static void xe_gt_fini(void *arg)
        for (i = 0; i < XE_ENGINE_CLASS_MAX; ++i)
                xe_hw_fence_irq_finish(&gt->fence_irq[i]);
  
+	destroy_workqueue(gt->submit_wq);
+
        xe_gt_disable_host_l2_vram(gt);
  }
  
@@ -716,6 +718,11 @@ int xe_gt_init(struct xe_gt *gt)
  
  	INIT_WORK(&gt->reset.worker, gt_reset_worker);
  
+	gt->submit_wq = alloc_ordered_workqueue("xe-submit-gt%u",
+                                               WQ_MEM_RECLAIM, gt->info.id);
+       if (IS_ERR(gt->submit_wq))
+               return PTR_ERR(gt->submit_wq);
+
        for (i = 0; i < XE_ENGINE_CLASS_MAX; ++i) {
                gt->ring_ops[i] = xe_ring_ops_get(gt, i);
                xe_hw_fence_irq_init(&gt->fence_irq[i]);
diff --git a/drivers/gpu/drm/xe/xe_gt_types.h b/drivers/gpu/drm/xe/xe_gt_types.h
index e5588c88800a..175c42672546 100644
--- a/drivers/gpu/drm/xe/xe_gt_types.h
+++ b/drivers/gpu/drm/xe/xe_gt_types.h
@@ -248,6 +248,9 @@ struct xe_gt {
        /** @exec_queue_ops: submission backend exec queue operations */
        const struct xe_exec_queue_ops *exec_queue_ops;
  
+	/** @submit_wq: ... */
+       struct workqueue_struct *submit_wq;
+
        /**
         * @ring_ops: ring operations for this hw engine (1 per engine class)
         */
diff --git a/drivers/gpu/drm/xe/xe_guc_submit.c 
b/drivers/gpu/drm/xe/xe_guc_submit.c
index 9458bf477fa6..858f84dc8fed 100644
--- a/drivers/gpu/drm/xe/xe_guc_submit.c
+++ b/drivers/gpu/drm/xe/xe_guc_submit.c
@@ -1928,11 +1928,12 @@ static int guc_exec_queue_init(struct xe_exec_queue *q)
        struct xe_gpu_scheduler *sched;
        struct xe_guc *guc = exec_queue_to_guc(q);
        struct workqueue_struct *submit_wq = NULL;
+       struct xe_gt *gt = guc_to_gt(guc);
        struct xe_guc_exec_queue *ge;
        long timeout;
        int err, i;
  
-	xe_gt_assert(guc_to_gt(guc), xe_device_uc_enabled(guc_to_xe(guc)));
+       xe_gt_assert(gt, xe_device_uc_enabled(guc_to_xe(guc)));
  
  	ge = kzalloc_obj(*ge);
        if (!ge)
@@ -1964,12 +1965,14 @@ static int guc_exec_queue_init(struct xe_exec_queue *q)
                struct xe_exec_queue *primary = 
xe_exec_queue_multi_queue_primary(q);
  
  		submit_wq = primary->guc->sched.base.submit_wq;
+       } else {
+               submit_wq = gt->submit_wq;
        }
  
  	err = xe_sched_init(&ge->sched, &drm_sched_ops, &xe_sched_ops,
-                           submit_wq, xe_lrc_ring_size() / MAX_JOB_SIZE_BYTES, 
64,
-                           timeout, guc_to_gt(guc)->ordered_wq, NULL,
-                           q->name, gt_to_xe(q->gt)->drm.dev);
+                           submit_wq, xe_lrc_ring_size() / MAX_JOB_SIZE_BYTES,
+                           64, timeout, gt->ordered_wq, NULL, q->name,
+                           gt_to_xe(gt)->drm.dev);
        if (err)
                goto err_release_id;
  
--
2.54.0