[PATCH 0/2] gpu/buddy: make range-biased allocation independent of live blocks

[William Palacek <William.Palacek@amd.com>]

A range-restricted allocation walks every split block in the range, so
its cost grows linearly with the number of live allocations there.
amdgpu restricts every VRAM allocation to its memory partition under
NPS2/NPS4, so on MI300X in CPX/NPS4 KFD allocation latency grows with
every live BO, under a VRAM manager lock shared by the compute
partitions.

Patch 1 looks up the lowest free block inside the range in the
offset-sorted free trees and restricts the existing walk to that
block's ancestors. Patch 2 adds a KUnit test for the NPS4 pattern
(range-biased, cleared, 64 KiB): about 1 s before, 2 ms after.

This is based on amd-staging-drm-next. drm-misc-next no longer has
separate clear and dirty free trees, so the lookup there needs a
different form and will be handled separately.

William Palacek (2):
  gpu/buddy: find range-biased blocks in the free trees
  gpu/tests/buddy: add range-biased allocation performance test

 drivers/gpu/buddy.c                | 36 ++++++++++++++++++++++++++++++
 drivers/gpu/tests/gpu_buddy_test.c | 25 +++++++++++++++++++++
 2 files changed, 61 insertions(+)

-- 
2.43.0