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mlx/mlx/backend/cuda/quantized/quantized.cpp
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2026-01-27 06:33:06 -08:00

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// Copyright © 2025 Apple Inc.
#include "mlx/backend/cuda/quantized/quantized.h"
#include "mlx/backend/cuda/device.h"
#include "mlx/backend/cuda/quantized/qmv.h"
#include "mlx/backend/cuda/quantized/quantized_utils.h"
#include "mlx/fast_primitives.h"
#include "mlx/primitives.h"
#include <nvtx3/nvtx3.hpp>
namespace mlx::core {
void QuantizedMatmul::eval_gpu(const std::vector<array>& inputs, array& out) {
nvtx3::scoped_range r("QuantizedMatmul::eval_gpu");
auto& s = stream();
auto& d = cu::device(s.device);
auto& enc = d.get_command_encoder(s);
out.set_data(cu::malloc_async(out.nbytes(), enc));
// Make sure the last two dims of x and w, s, b are contiguous. This should
// be relaxed for x.
array x = ensure_row_contiguous_matrix(inputs[0], enc, s);
array w = ensure_row_contiguous_matrix(inputs[1], enc, s);
array scales = ensure_row_contiguous_matrix(inputs[2], enc, s);
std::optional<array> biases = std::nullopt;
if (inputs.size() == 4) {
biases = ensure_row_contiguous_matrix(inputs[3], enc, s);
}
bool non_batched = w.ndim() == 2 && x.flags().row_contiguous;
int K = x.shape(-1);
int M = non_batched ? x.size() / K : x.shape(-2);
int N = out.shape(-1);
if (M > 8 || !transpose_ || mode_ == QuantizationMode::Affine) {
throw std::runtime_error("QMM NYI");
}
if (transpose_) {
fp_qmv(w, scales, x, out, bits_, group_size_, M, N, K, enc);
return;
}
}
void fast::Quantize::eval_gpu(
const std::vector<array>& inputs,
std::vector<array>& outputs) {
nvtx3::scoped_range r("Quantize::eval_gpu");
auto& s = stream();
auto& d = cu::device(s.device);
auto& enc = d.get_command_encoder(s);
if (dequantize_) {
auto wq = ensure_row_contiguous(inputs[0], enc, s);
auto scales = ensure_row_contiguous(inputs[1], enc, s);
auto& w = outputs[0];
w.set_data(cu::malloc_async(w.nbytes(), enc));
if (mode_ == QuantizationMode::Affine) {
auto biases = ensure_row_contiguous(inputs[2], enc, s);
affine_dequantize(wq, scales, biases, w, group_size_, bits_, enc, s);
} else {
fp_dequantize(wq, scales, w, group_size_, bits_, enc, s);
}
} else {
auto w = ensure_contiguous(inputs[0], enc, s);
auto& wq = outputs[0];
auto& scales = outputs[1];
wq.set_data(cu::malloc_async(wq.nbytes(), enc));
scales.set_data(cu::malloc_async(scales.nbytes(), enc));
if (mode_ == QuantizationMode::Affine) {
auto& biases = outputs[2];
biases.set_data(cu::malloc_async(biases.nbytes(), enc));
affine_quantize(w, wq, scales, biases, group_size_, bits_, enc, s);
} else {
fp_quantize(w, wq, scales, group_size_, bits_, enc, s);
}
}
}
} // namespace mlx::core