std::hardware_destructive_interference_size, std::hardware_constructive_interference_size

Threads

(C++11)

hardware_destructive_interference_sizehardware_constructive_interference_size

(C++17)(C++17)

this_thread namespace

get_id (C++11)
yield (C++11)

sleep_for (C++11)
sleep_until (C++11)

Mutual exclusion

mutex (C++11)
recursive_mutex (C++11)
shared_mutex (C++17)

timed_mutex (C++11)
recursive_timed_mutex (C++11)
shared_timed_mutex (C++14)

Generic lock management

lock_guard (C++11)
scoped_lock (C++17)
unique_lock (C++11)
shared_lock (C++14)
defer_lock_ttry_to_lock_tadopt_lock_t (C++11)(C++11)(C++11)

lock (C++11)
try_lock (C++11)
defer_locktry_to_lockadopt_lock (C++11)(C++11)(C++11)
once_flag (C++11)
call_once (C++11)

Condition variables

condition_variable

(C++11)

condition_variable_any

(C++11)

notify_all_at_thread_exit

(C++11)

cv_status

(C++11)

Futures

promise (C++11)
future (C++11)
shared_future (C++11)
packaged_task (C++11)
async (C++11)

launch (C++11)
future_status (C++11)
future_error (C++11)
future_category (C++11)
future_errc (C++11)

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);

Notes

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

Language
Standard library headers
Concepts
Utilities library
Strings library
Containers library
Algorithms library
Iterators library
Numerics library
Input/output library
Localizations library
Regular expressions library (C++11)
Atomic operations library (C++11)
Thread support library (C++11)
Filesystem library (C++17)
Technical Specifications

std::hardware_destructive_interference_size, std::hardware_constructive_interference_size

Notes

Example

See also