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#include <ATen/ATen.h>
#include <ATen/AccumulateType.h>
#include <ATen/cuda/CUDAContext.h>
#include <ATen/cuda/Exceptions.h>
// Another possibility:
// #include <torch/all.h>
#include <assert.h>
#include "type_shim.h"
#include "multi_tensor_apply.cuh"
#define BLOCK_SIZE 512
#define ILP 4
template<typename x_t>
struct L2NormFunctor
{
__device__ __forceinline__ void operator()(
int chunk_size,
volatile int* noop_gmem,
TensorListMetadata<1>& tl,
float* output,
float* output_per_tensor,
bool per_tensor,
int max_chunks_per_tensor)
{
// I'd like this kernel to propagate infs/nans.
// if(*noop_gmem == 1)
// return;
int tensor_loc = tl.block_to_tensor[blockIdx.x];
int chunk_idx = tl.block_to_chunk[blockIdx.x];
int n = tl.sizes[tensor_loc];
x_t* x = (x_t*)tl.addresses[0][tensor_loc];
x += chunk_idx*chunk_size;
n -= chunk_idx*chunk_size;
__shared__ float s_vals[512];
float vals[ILP]; // = {0}; // this probably works too but I want to be sure...
for(int i = 0; i < ILP; i++)
vals[i] = 0.f;
for(int i_start = 0; i_start < n && i_start < chunk_size; i_start += blockDim.x*ILP)
{
#pragma unroll
for(int ii = 0; ii < ILP; ii++)
{
int i = i_start + threadIdx.x + ii*blockDim.x;
if(i < n && i < chunk_size)
{
float next = static_cast<float>(x[i]);
vals[ii] += next*next;
}
}
}
float val = 0.f;
for(int i = 0; i < ILP; i++)
val += vals[i];
float final = reduce_block_into_lanes(s_vals, val);
if(threadIdx.x == 0)
{
if(!isfinite(final))
*noop_gmem = 1; // Blindly fire off a write. These will race but that's ok.
output[blockIdx.x] += final;
if(per_tensor)
output_per_tensor[(tl.start_tensor_this_launch + tensor_loc)*max_chunks_per_tensor + chunk_idx] = final;
}
}
};
__global__ void cleanup(
float* output,
float* output_per_tensor,
float* ret,
float* ret_per_tensor,
bool per_tensor,
int max_chunks_per_tensor)
{
__shared__ float vals[512];
if(blockIdx.x == 0)
{
float val = 0;
if(threadIdx.x < 320)
val = output[threadIdx.x];
float final = reduce_block_into_lanes(vals, val);
if(threadIdx.x == 0)
*ret = sqrt(final);
}
if(per_tensor)
{
float* output_this_tensor = output_per_tensor + blockIdx.x*max_chunks_per_tensor;
float val = 0;
for(int i = threadIdx.x; i < max_chunks_per_tensor; i += blockDim.x)
val += output_this_tensor[i];
float final = reduce_block_into_lanes(vals, val);
if(threadIdx.x == 0)
ret_per_tensor[blockIdx.x] = sqrt(final);
}
}
std::tuple<at::Tensor, at::Tensor> multi_tensor_l2norm_cuda(
int chunk_size,
at::Tensor noop_flag,
std::vector<std::vector<at::Tensor>> tensor_lists,
at::optional<bool> per_tensor_python)
{
bool per_tensor = per_tensor_python.has_value() ? per_tensor_python.value() : false;
auto float_options = tensor_lists[0][0].options().dtype(at::kFloat);
auto output = at::zeros({320}, float_options);
at::Tensor output_per_tensor;
at::Tensor ret_per_tensor;
int ntensors = tensor_lists[0].size();
int max_chunks_per_tensor = -1;
if(per_tensor)
{
for(int t = 0; t < ntensors; t++)
{
int max_chunks_this_tensor = (tensor_lists[0][t].numel() + chunk_size - 1)/chunk_size;
if(max_chunks_this_tensor > max_chunks_per_tensor)
max_chunks_per_tensor = max_chunks_this_tensor;
}
output_per_tensor = at::zeros({ntensors*max_chunks_per_tensor}, float_options);
ret_per_tensor = at::empty({ntensors}, float_options);
}
else
{
ret_per_tensor = at::empty({0}, float_options);
}
DISPATCH_FLOAT_AND_HALF(tensor_lists[0][0].scalar_type(), 0, "multi_tensor_l2norm_cuda",
multi_tensor_apply<1>(
BLOCK_SIZE,
chunk_size,
noop_flag,
tensor_lists,
L2NormFunctor<scalar_t_0>(),
output.data<float>(),
per_tensor ? output_per_tensor.data<float>() : nullptr,
per_tensor,
max_chunks_per_tensor);)
AT_CUDA_CHECK(cudaGetLastError());
// AT_CUDA_CHECK(cudaDeviceSynchronize());
// This involves one more small kernel launches, but will be negligible end to end.
// I could get rid of these by hacking the functor + multi tensor harness with persistence
// logic, but keeping it simple for now
auto ret = at::empty({1}, output.options());
auto stream = at::cuda::getCurrentCUDAStream();
cleanup<<<per_tensor ? ntensors : 1, 512, 0, stream>>>(
output.data<float>(),
per_tensor ? output_per_tensor.data<float>() : nullptr,
ret.data<float>(),
per_tensor ? ret_per_tensor.data<float>() : nullptr,
per_tensor,
max_chunks_per_tensor);
return std::tuple<at::Tensor, at::Tensor>(ret, ret_per_tensor);
}
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