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std::hardware_destructive_interference_size, std::hardware_constructive_interference_size

From cppreference.com
< cpp‎ | thread
 
 
Thread support library
Threads
(C++11)
hardware_destructive_interference_sizehardware_constructive_interference_size
(C++17)(C++17)
this_thread namespace
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Mutual exclusion
(C++11)
Generic lock management
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Condition variables
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Defined in header <new>
inline constexpr std::size_t
    hardware_destructive_interference_size = /*implementation-defined*/;
(1) (since C++17)
inline constexpr std::size_t
    hardware_constructive_interference_size = /*implementation-defined*/;
(2) (since C++17)
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 {
  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);

[edit] Notes

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

[edit] Example

[edit] See also

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