如何在 C++ 程序中使用 hbw_malloc 库？

Question

我希望能够使用 hbwmalloc 库直接在 MCDRAM 上分配 Vectors 等 C++ 对象。问题是只实现了 C malloc。因此，我考虑编写一个 Vector 的子类来实现调整大小，使用 hbw_malloc.

动态分配保留

这将允许程序员选择分配数据的 NUMA 节点。

这是做我想做的最好的主意吗？

Answer 1

你可以这样做：

#include <hbwmalloc.h> // hbw_check_available, hbw_malloc, hbw_free
#include <cstddef>     // std::size_t
#include <cstdint>     // std::intptr_t
#include <stdexcept>   // std::logic_error
#include <new>         // std::bad_alloc
#include <memory>      // std::addressof

#define do_hbw_check_available

template <class T>
struct hbw_allocator
{
    using value_type = T;
    using pointer = T*;
    using const_pointer = const T*;
    using reference = T&;
    using const_reference = const T&;
    using size_type = std::size_t;
    using difference_type = std::intptr_t;

    static pointer allocate(size_type n)
    {
#if defined(do_hbw_check_available)
        if (0 != hbw_check_available())
        {
            throw std::logic_error("HBW not available");
        }
#endif

        // Calculate size of storage with alignment and padding
        const size_type size = sizeof(value_type) * n;

        // Allocate storage
        pointer p = hbw_malloc(size);

        // Ensure that memory was in fact allocated
        if (nullptr == p)
        {
            throw std::bad_alloc();
        }

        return p;
    }

    static void deallocate(const_pointer p, size_type /* n */)
    {
        hbw_free(p);
    }

    void construct(pointer p, const_reference t)
    {
        // Call copy-constructor of the element pointed to by p
        new ((void*) p) value_type(t);
    }

    void destroy(pointer p)
    {
        // Call destructor of the element pointed to by p
        p->~value_type();
    }

    size_type max_size () const
    {
        return size_type(-1) / sizeof(value_type);
    }

    bool operator!=(const hbw_allocator<value_type>& arg) const
    {
        return !(*this == arg);
    }

    // Returns true if and only if storage allocated from *this can be deallocated from other, and vice versa.
    // Always returns true for stateless allocators.
    bool operator==(const hbw_allocator<value_type>& /* arg */) const
    {
        return true;
    }

    pointer adress(reference arg)
    {
        return std::addressof(arg);
    }

    const_pointer adress(const_reference arg) const
    {
        return std::addressof(arg);
    }

    template <class U>
    struct rebind
    {
        using other = hbw_allocator<U>;
    };
};

示例：

然后您可以像这样使用它：

template <class T>
using hbw_vector = std::vector<T, hbw_allocator<T>>;

hbw_vector<int> vec(5);

Answer 2

memkind library (which provides you an easy access to MCDRAM) already provides a C++ allocator for you. See this manual entry了解更多信息。

用法很简单，如本例所示

#include <hbw_allocator.h>
#include <vector>
#include <assert.h>

int main(int argc, char*argv[])
{
        std::vector<unsigned, hbw::allocator<unsigned> > v;
        v.push_back (123);
        assert(v.size() == 1);
        assert(v[0] == 123);
        return 0;
}

如何在 C++ 程序中使用 hbw_malloc 库？

How to use hbw_malloc library within C++ program?

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