这种全局序列一致性带来更多的同步成本，因此在性能上memory_order_acq_rel通常优于memory_order_seq_cst...
而memory_order_seq_cst能保证在单线程中的所有原子操作有序 memory_order_seq_cst保证的是在当前线程...
memory_order_seq_cst,即顺序一致性模型。 Acquire-Release 模式 memory_order_release前面不会被reord到本句之后;memory_order_acquire之后的代码不会被reorder到本句之前;memory_order_acq_rel同时包含acquire和release标志。 这是一段实践代码,代码简单明确:https://www.cnblogs.com/lizhanzhe/p/10893016.html #in...
inline constexpr memory_order memory_order_acquire = memory_order::acquire; inline constexpr memory_order memory_order_release = memory_order::release; inline constexpr memory_order memory_order_acq_rel = memory_order::acq_rel; inline constexpr memory_order memory_order_seq_cst = memory_order:...
memory_order_acq_rel memory_order_seq_cst 1. 2. 3. 4. 5. 6. memory_order_relaxed:只保证当前操作的原子性,不考虑线程间的同步,其他线程可能读到新值,也可能读到旧值。比如 C++ shared_ptr 里的引用计数,我们只关心当前的应用数量,而不关心谁在引用谁在解引用。
memory_order_consume, memory_order_acquire, memory_order_release, memory_order_acq_rel, memory_order_seq_cst }; 上述6 中访存次序(内存序)分为 3 类,顺序一致性模型(std::memory_order_seq_cst),Acquire-Release 模型(std::memory_order_consume, std::memory_order_acquire, std::memory_order_releas...
在C11/C++11 中,引入了六种不同的 memory order,可以让程序员在并发编程中根据自己需求尽可能降低同步的粒度,以获得更好的程序性能。 这六种 order 分别是: relaxed, acquire, release, consume, acq_rel, seq_cst RocksDB SkipList Memory Order
typedefenummemory_order{memory_order_relaxed,memory_order_consume,memory_order_acquire,memory_order_release,memory_order_acq_rel,memory_order_seq_cst}memory_order; 限于篇幅,这里只介绍memory_order_acquire(简称Acquire)和memory_order_release(简称Release)这两种内存顺序,后续再介绍C++的其他内存顺序。 下表...
typedefenum{memory_order_relaxed=__ATOMIC_RELAXED,memory_order_consume=__ATOMIC_CONSUME,memory_order_acquire=__ATOMIC_ACQUIRE,memory_order_release=__ATOMIC_RELEASE,memory_order_acq_rel=__ATOMIC_ACQ_REL,memory_order_seq_cst=__ATOMIC_SEQ_CST}memory_order; ...
不同的内存顺序有不同的语义, 会实现不同的顺序模型 (order model), 性能也各不相同. C 中有六种内存顺序 enum memory_order { memory_order_relaxed, memory_order_consume, memory_order_acquire, memory_order_release, memory_order_acq_rel, memory_order_seq_cst, }; 这六种内存顺序相互组合可以实现...