[PATCH v4 0/4] Use new dma-map IOVA alloc, link, and sync API in GPU SVM and DRM pagemap

Matthew Brost
2026-02-05T04:19:28Z

The dma-map IOVA alloc, link, and sync APIs perform significantly better
than dma-map / dma-unmap, as they avoid costly IOMMU synchronizations.
This difference is especially noticeable when mapping a 2MB region in
4KB pages.

Use dma-map IOVA alloc, link, and sync APIs for GPU SVM and DRM page,
which mappings between the CPU and GPU.

Initial results are promising.

Baseline CPU time during 2M / 64K fault with a migration:
Average migrate 2M cpu time (us, percentage): 333.99665178571428571429, .61102853199282922865
Average migrate 64K cpu time (us, percentage): 18.62723214285714285714, .30127985269960467173

After this series CPU time during 2M / 64K fault with a migration:
Average migrate 2M cpu time (us, percentage): 224.81808035714285714286, .51412827364772602557
Average migrate 64K cpu time (us, percentage): 14.65625000000000000000, .25659463050529524405

Matt

v2:
- Include missing basline patch for CI
v3:
- Fix memory corruption
- PoC IOVA alloc for multi-GPU
v4:
- Pack IOVA / drop dummy pages
- Drop multi-GPU IOVA alloc

Francois Dugast (1):
drm/pagemap: Add helper to access zone_device_data

Matthew Brost (3):
drm/gpusvm: Use dma-map IOVA alloc, link, and sync API in GPU SVM
drm/pagemap: Split drm_pagemap_migrate_map_pages into device / system
drm/pagemap: Use dma-map IOVA alloc, link, and sync API for DRM
pagemap

drivers/gpu/drm/drm_gpusvm.c | 62 +++++++--
drivers/gpu/drm/drm_pagemap.c | 229 +++++++++++++++++++++++++---------
include/drm/drm_gpusvm.h | 5 +
include/drm/drm_pagemap.h | 14 +++
4 files changed, 238 insertions(+), 72 deletions(-)

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2.34.1