std::hardware_destructive_interference_size,std::hardware_constructive_interference_size (3) - Linux Man Pages

std::hardware_destructive_interference_size,std::hardware_constructive_interference_size: std::hardware_destructive_interference_size,std::hardware_constructive_interference_size

NAME

std::hardware_destructive_interference_size,std::hardware_constructive_interference_size - std::hardware_destructive_interference_size,std::hardware_constructive_interference_size

Synopsis


Defined in header <new>
inline constexpr std::size_t (1) (since C++17)
hardware_destructive_interference_size = /*implementation-defined*/;
inline constexpr std::size_t (2) (since C++17)
hardware_constructive_interference_size = /*implementation-defined*/;


1) Minimum offset between two objects to avoid false sharing. Guaranteed to be at least alignof(std::max_align_t)


  struct keep_apart {
    alignas(std::hardware_destructive_interference_size) std::atomic<int> cat;
    alignas(std::hardware_destructive_interference_size) std::atomic<int> dog;
  };


2) Maximum size of contiguous memory to promote true sharing. Guaranteed to be at least alignof(std::max_align_t)


  struct together {
    std::atomic<int> dog;
    int puppy;
  };
  struct kennel {
    // Other data members...
    alignas(sizeof(together)) together pack;
    // Other data members...
  };
  static_assert(sizeof(together) <= std::hardware_constructive_interference_size);

Notes


These constants provide a portable way to access the L1 data cache line size.

Example


 This section is incomplete
 Reason: no example

See also


hardware_concurrency returns the number of concurrent threads supported by the implementation
                     (public static member function of std::thread)
[static]