Fix cuda arg reduce (#2291)

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Awni Hannun 2025-06-14 17:54:00 -07:00 committed by GitHub
parent a6d780154f
commit a14aaa7c9d
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3 changed files with 12 additions and 6 deletions

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@ -1,5 +1,4 @@
// Copyright © 2025 Apple Inc.
#include "mlx/backend/common/utils.h"
#include "mlx/backend/cuda/device.h"
#include "mlx/backend/cuda/iterators/strided_iterator.cuh"
@ -113,7 +112,7 @@ __global__ void arg_reduce_general(
for (int r = 0; r < cuda::ceil_div(axis_size, BLOCK_DIM * N_READS); ++r) {
T vals[N_READS];
auto tid = r * BLOCK_DIM + block.thread_index().z;
auto tid = r * BLOCK_DIM + block.thread_index().x;
cub::LoadDirectBlocked(
tid, strided_iterator(in + in_idx, axis_stride), vals, axis_size, init);
best = op.reduce_many(best, vals, tid * N_READS);
@ -158,7 +157,7 @@ void ArgReduce::eval_gpu(const std::vector<array>& inputs, array& out) {
constexpr uint32_t N_READS = 4;
MLX_SWITCH_BLOCK_DIM(cuda::ceil_div(axis_size, N_READS), BLOCK_DIM, {
dim3 num_blocks = get_2d_grid_dims(out.shape(), out.strides());
dim3 block_dims{1, 1, BLOCK_DIM};
dim3 block_dims{BLOCK_DIM, 1, 1};
auto kernel = &cu::arg_reduce_general<
InType,
cu::ArgMax<InType>,

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@ -5,6 +5,7 @@
#include "mlx/backend/gpu/copy.h"
#include "mlx/dtype_utils.h"
#include "mlx/primitives.h"
#include "mlx/utils.h"
#include <cublasLt.h>
#include <fmt/format.h>
@ -45,7 +46,7 @@ class MatMul {
heuristic_.state = CUBLAS_STATUS_NOT_INITIALIZED;
auto scale_type = dtype_to_cuda_type(dtype);
if (dtype == bfloat16) {
if (dtype == bfloat16 || dtype == float16) {
scale_type = CUDA_R_32F;
}
CHECK_CUBLAS_ERROR(cublasLtMatmulDescCreate(
@ -192,11 +193,12 @@ class MatMul {
cublasComputeType_t dtype_to_compute_type(Dtype dtype) {
switch (dtype) {
case float16:
return CUBLAS_COMPUTE_16F;
return CUBLAS_COMPUTE_32F;
case bfloat16:
return CUBLAS_COMPUTE_32F;
case float32:
return CUBLAS_COMPUTE_32F;
return mlx::core::env::enable_tf32() ? CUBLAS_COMPUTE_32F_FAST_TF32
: CUBLAS_COMPUTE_32F;
case float64:
case complex64:
return CUBLAS_COMPUTE_64F;

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@ -149,6 +149,11 @@ inline bool metal_fast_synch() {
return metal_fast_synch;
}
inline bool enable_tf32() {
static bool enable_tf32_ = get_var("MLX_ENABLE_TF32", 1);
return enable_tf32_;
}
} // namespace env
} // namespace mlx::core