Optimization: Investigate huge pages for particle arrays cpu alloc

[PhilipDeegan]

I have a vague recollection of testing this already but I'm not 100%

sample code

#include <limits>
#include <thread>
#include <new>
#include <stdlib.h>   // posix_memalign
#include <sys/mman.h> // madvise

template <typename T> struct thp_allocator {
  constexpr static std::size_t huge_page_size = 1 << 21; // 2 MiB
  using value_type = T;

  thp_allocator() = default;
  template <class U>
  constexpr thp_allocator(const thp_allocator<U> &) noexcept {}

  T *allocate(std::size_t n) {
    if (n > std::numeric_limits<std::size_t>::max() / sizeof(T)) {
      throw std::bad_alloc();
    }
    void *p = nullptr;
    posix_memalign(&p, huge_page_size, n * sizeof(T));
    madvise(p, n * sizeof(T), MADV_HUGEPAGE);
    if (p == nullptr) {
      throw std::bad_alloc();
    }
    return static_cast<T *>(p);
  }

  void deallocate(T *p, std::size_t n) { std::free(p); }
};

int main(){
    
    thp_allocator<double> thp;
    auto m = thp.allocate(1000);
}