std::hardware_destructive_interference_size, std::hardware_constructive_interference_size
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 {
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
See also
[static] | returns the number of concurrent threads supported by the implementation (public static member function of std::thread ) |
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