memory_order_relaxed memory_order_acquire 详解memory_order_relaxed和memory_order_acquire是C++中的原子操作(memory order)选项,用于控制多线程之间对共享变量的访问和修改顺序。 memory_order_relaxed:这是最轻松的内存顺序,不提供任何同步保证。当使用此内存顺序时,不会发生任何同步或顺序限制,线程可以以任意顺序读取...
memory_order_acquire:(可以理解为 mutex 的 lock 操作) 对读取施加 acquire 语义(load),在代码中这条语句后面所有读写操作都无法重排到这个操作之前,即 load-store 不能重排为 store-load, load-load 也无法重排为 load-load 在这个原子变量上施加 release 语义的操作发生之后,acquire 可以保证读到所有在 release...
store函数可使用:memory_order_seq_cst、memory_order_release、memory_order_relaxed load函数可使用:memory_order_seq_cst、memory_order_acquire、memory_order_consume、memory_order_relaxed 需要同时读写的操作,如test_and_flag、exchange等操作, 除了memory_order_acq_rel不能使用,其他5种都能使用。 原子类型提供...
更强的内存顺序也没有有意义的延迟优势，即使看到keep_running或exit_now标志更改的延迟很重要。IDK为什么...
But since C++11's design forconsumewas impractical for compilers to implement, they all just gave up and strengthen it toacquire, requiring a memory barrier on most weakly-ordered ISAs. (e.g. POWER or ARM, but not x86). So in real life, to get that juicy performance for re...
...C++11中的内存模型通过std::memory_order枚举定义了如下内存序: enum memory_order { memory_order_relaxed, memory_order_consume..., memory_order_acquire, memory_order_release, memory_order_acq_rel,memory_order_seq_cst}; 以上六种内存序分别代表不同的同步和顺序关系...1.6 Sequentially ...
现代计算机体系结构上，CPU执行指令的速度远远大于CPU访问内存的速度，于是引入Cache机制来加速内存访问速度...
松弛加载不与其之前或之后的任何其他加载/存储同步。还要注意，内存顺序语义是关于与syncronization变量相关的...
fetch_sub(1, std::memory_order_release) == 1) { std::atomic_thread_fence(std::memory_order_acquire); // delete managed memory } Share Improve this answer Follow edited Jun 20, 2020 at 9:12 CommunityBot 111 silver badge answered Jan 8, 2018 at 10:24 LWimsey...
int x = a.fetch_add(1, std::memory_order_relaxed);编译出来就是两条指令：movl $1, %edx...