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[ROCm] Fix non-stride-one backwards indexing performance #2693

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Merged
merged 1 commit into from
Oct 8, 2025
Merged

[ROCm] Fix non-stride-one backwards indexing performance #2693

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40 changes: 35 additions & 5 deletions aten/src/ATen/native/cuda/Indexing.cu
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Original file line number Diff line number Diff line change
Expand Up @@ -56,9 +56,10 @@ constexpr uint64_t getDefaultMaxThreadsPerBlock() {
#endif
}

#if 0
#ifdef USE_ROCM
#define SKIP_SORTED_INDICES 32
template <typename scalar_t, int SZ>
__global__ void indexing_backward_kernel(
__global__ void indexing_backward_kernel_many_indices(
const int64_t* sorted_indices, const int64_t* indices, const scalar_t* grad_output, scalar_t* grad_weight,
int64_t numel, int64_t stride, int64_t stride_before, int64_t outer_dim, bool accumulate) {
using opmath_t = at::opmath_type<scalar_t>;
Expand Down Expand Up @@ -141,10 +142,7 @@ __global__ void indexing_backward_kernel(
}
}
}
#endif

#ifdef USE_ROCM
#define SKIP_SORTED_INDICES 32
template <typename scalar_t>
__global__ void indexing_backward_kernel_stride_1(
const int64_t* sorted_indices, const int64_t* indices, const scalar_t* grad_output, scalar_t* grad_weight,
Expand Down Expand Up @@ -784,6 +782,38 @@ void index_put_with_sort_kernel(Tensor & self, const c10::List<std::optional<Ten
kBool,
kBFloat16);
} else {
#ifdef USE_ROCM
if (num_indices >= 200000)
AT_DISPATCH_V2(
expandedValue.scalar_type(),
"indexing_backward_many_indices",
AT_WRAP([&] {
indexing_backward_kernel_many_indices<scalar_t, UNROLL><<<new_grid, block, smem_dups_size, stream>>>(
sorted_indices.const_data_ptr<int64_t>(),
orig_indices.const_data_ptr<int64_t>(),
expandedValue.const_data_ptr<scalar_t>(),
src_.mutable_data_ptr<scalar_t>(),
num_indices,
sliceSize,
strideBefore,
nElemBefore,
accumulate);
C10_CUDA_KERNEL_LAUNCH_CHECK();
}),
AT_EXPAND(AT_ALL_TYPES_AND_COMPLEX),
// AT_EXPAND(AT_FLOAT8_TYPES),
// TODO(#113663): clean up accumulation behavior in float8 dtypes, accumulate=True
// should not be supported here, then reenable AT_FLOAT8_DTYPES
kFloat8_e4m3fn,
kFloat8_e5m2,
kFloat8_e4m3fnuz,
kFloat8_e5m2fnuz,
kComplexHalf,
kHalf,
kBool,
kBFloat16);
else
#endif
AT_DISPATCH_V2(
expandedValue.scalar_type(),
"indexing_backward",
Expand Down