Difference between revisions of "cpp/thread/hardware destructive interference size"
From cppreference.com
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| − | @2@ Maximum size of contiguous memory to promote true sharing. Guaranteed to be at least {{c|alignof(max_align_t)}} | + | @2@ Maximum size of contiguous memory to promote true sharing. Guaranteed to be at least {{c|alignof(std::max_align_t)}} |
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struct together { | struct together { | ||
Revision as of 03:31, 15 November 2016
| Defined in header <new>
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| static constexpr std::size_t hardware_destructive_interference_size = /*implementation-defined*/; |
(1) | (since C++17) |
| static 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);
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
| [static] |
returns the number of concurrent threads supported by the implementation (public static member function of std::{{{1}}})
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