From: Honglei Huang <[email protected]>
Hi all,
This is v3 of the patch series to support allocating multiple non-contiguous
CPU virtual address ranges that map to a single contiguous GPU virtual address.
v3:
1. No new ioctl: Reuses existing AMDKFD_IOC_ALLOC_MEMORY_OF_GPU
- Adds only one flag: KFD_IOC_ALLOC_MEM_FLAGS_USERPTR_BATCH
- When flag is set, mmap_offset field points to range array
- Minimal API surface change
2. Improved MMU notifier handling:
- Single mmu_interval_notifier covering the VA span [va_min, va_max]
- Interval tree for efficient lookup of affected ranges during invalidation
- Avoids per-range notifier overhead mentioned in v2 review
3. Better code organization: Split into 8 focused patches for easier review
v2:
- Each CPU VA range gets its own mmu_interval_notifier for invalidation
- All ranges validated together and mapped to contiguous GPU VA
- Single kgd_mem object with array of user_range_info structures
- Unified eviction/restore path for all ranges in a batch
Current Implementation Approach
===============================
This series implements a practical solution within existing kernel constraints:
1. Single MMU notifier for VA span: Register one notifier covering the
entire range from lowest to highest address in the batch
2. Interval tree filtering: Use interval tree to efficiently identify
which specific ranges are affected during invalidation callbacks,
avoiding unnecessary processing for unrelated address changes
3. Unified eviction/restore: All ranges in a batch share eviction and
restore paths, maintaining consistency with existing userptr handling
Patch Series Overview
=====================
Patch 1/8: Add userptr batch allocation UAPI structures
- KFD_IOC_ALLOC_MEM_FLAGS_USERPTR_BATCH flag
- kfd_ioctl_userptr_range and kfd_ioctl_userptr_ranges_data structures
Patch 2/8: Add user_range_info infrastructure to kgd_mem
- user_range_info structure for per-range tracking
- Fields for batch allocation in kgd_mem
Patch 3/8: Implement interval tree for userptr ranges
- Interval tree for efficient range lookup during invalidation
- mark_invalid_ranges() function
Patch 4/8: Add batch MMU notifier support
- Single notifier for entire VA span
- Invalidation callback using interval tree filtering
Patch 5/8: Implement batch userptr page management
- get_user_pages_batch() and set_user_pages_batch()
- Per-range page array management
Patch 6/8: Add batch allocation function and export API
- init_user_pages_batch() main initialization
- amdgpu_amdkfd_gpuvm_alloc_memory_of_gpu_batch() entry point
Patch 7/8: Unify userptr cleanup and update paths
- Shared eviction/restore handling for batch allocations
- Integration with existing userptr validation flows
Patch 8/8: Wire up batch allocation in ioctl handler
- Input validation and range array parsing
- Integration with existing alloc_memory_of_gpu path
Testing
=======
- Multiple scattered malloc() allocations (2-4000+ ranges)
- Various allocation sizes (4KB to 1G+ per range)
- Memory pressure scenarios and eviction/restore cycles
- OpenCL CTS and HIP catch tests in KVM guest environment
- AI workloads: Stable Diffusion, ComfyUI in virtualized environments
- Small LLM inference (3B-7B models)
- Benchmark score: 160,000 - 190,000 (80%-95% of bare metal)
- Performance improvement: 2x-2.4x faster than userspace approach
Thank you for your review and feedback.
Best regards,
Honglei Huang
Honglei Huang (8):
drm/amdkfd: Add userptr batch allocation UAPI structures
drm/amdkfd: Add user_range_info infrastructure to kgd_mem
drm/amdkfd: Implement interval tree for userptr ranges
drm/amdkfd: Add batch MMU notifier support
drm/amdkfd: Implement batch userptr page management
drm/amdkfd: Add batch allocation function and export API
drm/amdkfd: Unify userptr cleanup and update paths
drm/amdkfd: Wire up batch allocation in ioctl handler
drivers/gpu/drm/amd/amdgpu/amdgpu_amdkfd.h | 23 +
.../gpu/drm/amd/amdgpu/amdgpu_amdkfd_gpuvm.c | 539 +++++++++++++++++-
drivers/gpu/drm/amd/amdkfd/kfd_chardev.c | 128 ++++-
include/uapi/linux/kfd_ioctl.h | 31 +-
4 files changed, 697 insertions(+), 24 deletions(-)
--
2.34.1
