[PATCH v4 0/7] Use DRM scheduler for delayed GT TLB invalidations

[Tvrtko Ursulin]

On 24/07/2025 20:12, Matthew Brost wrote:
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>        Use the DRM scheduler for delayed GT TLB invalidations, which properly
> fixes the issue raised in [1]. GT TLB fences have their own dma-fence
> context, so even if the invalidations are ordered, the dma-resv/DRM
> scheduler cannot squash the fences. This results in O(M*N*N) complexity
> in the garbage collector, where M is the number of ranges in the garbage
> collector and N is the number of pending GT TLB invalidations. After
> this change, the resulting complexity in O(M*C) where C is the number of
> TLB invalidation contexts (i.e., number of exec queue, GTs tuples) with
> an invalidation in flight.

Does this series improve the performance of the TLB invalidations in 
general?

I am asking because we are currently investigating a problem with Google 
Chrome which apparently suffers a lot from latencies caused by TLB 
invalidations piling up after a lot of tab switching causes a lot of vm 
bind ioctl activity.

Also, is it related to 
https://gitlab.freedesktop.org/drm/xe/kernel/-/issues/2162 ?

Regards,

Tvrtko

> Admittedly, it's quite a lot of code, but the series includes extensive
> kernel documentation and clear code comments. It introduces a generic
> dependency scheduler that can be reused in the future and is logically
> much cleaner than the previous open-coded solution for delaying GT TLB
> invalidations until a bind job completes.
> 
> v2:
>   - Various cleanup covered in detail in change logs
>   - Use a per-GT ordered workqueue as DRM scheduler workqueue
>   - Remove unused ftrace points
> v3:
>   - Address Stuarts feedback
>   - Fix kernel doc, minor cleanups
> v4:
>   - Rebase
> 
> Matt
> 
> [1] https://patchwork.freedesktop.org/patch/658370/?series=150188&rev=1
> 
> Matthew Brost (7):
>    drm/xe: Explicitly mark migration queues with flag
>    drm/xe: Add generic dependecy jobs / scheduler
>    drm/xe: Create ordered workqueue for GT TLB invalidation jobs
>    drm/xe: Add dependency scheduler for GT TLB invalidations to bind
>      queues
>    drm/xe: Add GT TLB invalidation jobs
>    drm/xe: Use GT TLB invalidation jobs in PT layer
>    drm/xe: Remove unused GT TLB invalidation trace points
> 
>   drivers/gpu/drm/xe/Makefile                 |   2 +
>   drivers/gpu/drm/xe/xe_dep_job_types.h       |  29 +++
>   drivers/gpu/drm/xe/xe_dep_scheduler.c       | 143 ++++++++++
>   drivers/gpu/drm/xe/xe_dep_scheduler.h       |  21 ++
>   drivers/gpu/drm/xe/xe_exec_queue.c          |  48 ++++
>   drivers/gpu/drm/xe/xe_exec_queue_types.h    |  15 ++
>   drivers/gpu/drm/xe/xe_gt_tlb_inval_job.c    | 274 ++++++++++++++++++++
>   drivers/gpu/drm/xe/xe_gt_tlb_inval_job.h    |  34 +++
>   drivers/gpu/drm/xe/xe_gt_tlb_invalidation.c |   8 +
>   drivers/gpu/drm/xe/xe_gt_types.h            |   2 +
>   drivers/gpu/drm/xe/xe_migrate.c             |  42 ++-
>   drivers/gpu/drm/xe/xe_migrate.h             |  13 +
>   drivers/gpu/drm/xe/xe_pt.c                  | 178 +++++--------
>   drivers/gpu/drm/xe/xe_trace.h               |  16 --
>   14 files changed, 700 insertions(+), 125 deletions(-)
>   create mode 100644 drivers/gpu/drm/xe/xe_dep_job_types.h
>   create mode 100644 drivers/gpu/drm/xe/xe_dep_scheduler.c
>   create mode 100644 drivers/gpu/drm/xe/xe_dep_scheduler.h
>   create mode 100644 drivers/gpu/drm/xe/xe_gt_tlb_inval_job.c
>   create mode 100644 drivers/gpu/drm/xe/xe_gt_tlb_inval_job.h
>