cuda_zero_copy.hpp

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#pragma once

#include <cstdlib>
#include <new>

#include <cuda_runtime.h>

template <class T>
struct CUDAZeroCopyAllocator
{
    typedef T value_type;
    CUDAZeroCopyAllocator() = default;
    template <class U>
    constexpr CUDAZeroCopyAllocator(const CUDAZeroCopyAllocator<U> &) noexcept {}
    T *allocate(std::size_t n)
    {
        if (n > std::size_t(-1) / sizeof(T))
            throw std::bad_alloc();
        T *p;
        cudaError_t err = cudaHostAlloc(&p, n * sizeof(T), cudaHostAllocMapped | cudaHostAllocPortable);
        if (err != cudaSuccess)
        {
            throw std::bad_alloc();
        }
        return p;
    }
    void deallocate(T *p, std::size_t) noexcept { cudaFreeHost(p); }
};
template <class T, class U>
bool operator==(const CUDAZeroCopyAllocator<T> &, const CUDAZeroCopyAllocator<U> &) { return true; }
template <class T, class U>
bool operator!=(const CUDAZeroCopyAllocator<T> &, const CUDAZeroCopyAllocator<U> &) { return false; }