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drm/xe: Use ordered wq for preempt fence waiting

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Preempt fences can sleep waiting for an exec queue suspend operation to
complete. If the system_unbound_wq is used for waiting and the number of
waiters exceeds max_active this will result in other users of the
system_unbound_wq getting starved. Use a device private work queue for
preempt fences to avoid starvation of the system_unbound_wq.

Even though suspend operations can complete out-of-order, all suspend
operations within a VM need to complete before the preempt rebind worker
can start. With that, use a device private ordered wq for preempt fence
waiting.

v2:
 - Add comment about cleanup on failure (Matt R)
 - Update commit message (Lucas)

Fixes: dd08ebf6c352 ("drm/xe: Introduce a new DRM driver for Intel GPUs")
Signed-off-by: Matthew Brost <matthew.brost@intel.com>
Reviewed-by: Lucas De Marchi <lucas.demarchi@intel.com>
Link: https://patchwork.freedesktop.org/patch/msgid/20240401221913.139672-2-matthew.brost@intel.com
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
(cherry picked from commit 37c15c4aae1fe3f67efd2641db8d8c25c2d524ab)
Signed-off-by: Lucas De Marchi <lucas.demarchi@intel.com>
This commit is contained in:
Matthew Brost 2024-04-01 15:19:11 -07:00 committed by Lucas De Marchi
parent 3edd52bead
commit 77a011012d
3 changed files with 14 additions and 2 deletions
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11
drivers/gpu/drm/xe/xe_device.c
View File

@ -193,6 +193,9 @@ static void xe_device_destroy(struct drm_device *dev, void *dummy)
{
struct xe_device *xe = to_xe_device(dev);
if (xe->preempt_fence_wq)
destroy_workqueue(xe->preempt_fence_wq);
if (xe->ordered_wq)
destroy_workqueue(xe->ordered_wq);
@ -258,9 +261,15 @@ struct xe_device *xe_device_create(struct pci_dev *pdev,
INIT_LIST_HEAD(&xe->pinned.external_vram);
INIT_LIST_HEAD(&xe->pinned.evicted);
xe->preempt_fence_wq = alloc_ordered_workqueue("xe-preempt-fence-wq", 0);
xe->ordered_wq = alloc_ordered_workqueue("xe-ordered-wq", 0);
xe->unordered_wq = alloc_workqueue("xe-unordered-wq", 0, 0);
if (!xe->ordered_wq || !xe->unordered_wq) {
if (!xe->ordered_wq || !xe->unordered_wq ||
!xe->preempt_fence_wq) {
/*
* Cleanup done in xe_device_destroy via
* drmm_add_action_or_reset register above
*/
drm_err(&xe->drm, "Failed to allocate xe workqueues\n");
err = -ENOMEM;
goto err;

3
drivers/gpu/drm/xe/xe_device_types.h
View File

@ -363,6 +363,9 @@ struct xe_device {
/** @ufence_wq: user fence wait queue */
wait_queue_head_t ufence_wq;
/** @preempt_fence_wq: used to serialize preempt fences */
struct workqueue_struct *preempt_fence_wq;
/** @ordered_wq: used to serialize compute mode resume */
struct workqueue_struct *ordered_wq;

2
drivers/gpu/drm/xe/xe_preempt_fence.c
View File

@ -49,7 +49,7 @@ static bool preempt_fence_enable_signaling(struct dma_fence *fence)
struct xe_exec_queue *q = pfence->q;
pfence->error = q->ops->suspend(q);
queue_work(system_unbound_wq, &pfence->preempt_work);
queue_work(q->vm->xe->preempt_fence_wq, &pfence->preempt_work);
return true;
}