[RFC PATCH v2 0/3] Use new dma-map IOVA alloc, link, and sync API in GPU SVM and DRM pagemap

[Matthew Brost <matthew.brost@intel.com>]

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): 552.36049107142857142857, .71943789893868318799
Average migrate 64K cpu time (us, percentage): 24.97767857142857142857, .34789908128526791960

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

Sending as an RFC as there appears to be intermittent memory corruptions
when running xe_exec_system_allocator that need to be tracked down.

Matt

v2:
 - Include missing basline patch for CI

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

Matthew Brost (2):
  drm/gpusvm: Use new dma-map IOVA alloc, link, and sync API in GPU SVM
  drm/pagemap: Use new dma-map IOVA alloc, link, and sync API for DRM
    pagemap

 drivers/gpu/drm/drm_gpusvm.c  |  70 ++++++++++-----
 drivers/gpu/drm/drm_pagemap.c | 156 +++++++++++++++++++++++++---------
 include/drm/drm_gpusvm.h      |   3 +
 include/drm/drm_pagemap.h     |  14 +++
 4 files changed, 183 insertions(+), 60 deletions(-)

-- 
2.34.1