比较并交换:a.compare_exchange_strong(b, c)或者a.compare_exchange_weak(b, c),如果a的值等于b,则将a设置为c,返回true,否则返回false。 尽管原子变量是多线程编程中非常重要的同步机制,但是它也存在一些局限性。具体来说,原子变量只能保证单个变量的原子性操作,而不能保证多个变量之间的同步。此外,原子变量也...
C* expected, C desired ); (1) (C11 起) _Bool atomic_compare_exchange_weak( volatile A *obj, C* expected, C desired ); (2) (C11 起) _Bool atomic_compare_exchange_strong_explicit( volatile A* obj, C* expected, C desired, memory_order succ, memory_order fail ); (3) (...
compare_exchange_weakis allowed to fail spuriously, that is, acts as if*this!=expectedeven if they are equal. When a compare-and-exchange is in a loop,compare_exchange_weakwill yield better performance on some platforms. Whencompare_exchange_weakwould require a loop andcompare_exchange_strongwo...
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Seeatomic::compare_exchange_strongfor the equivalent member function ofatomic. Parameters obj Pointer to anatomicobject. TypeArepresents other overloadedatomic types(if the library does not implement theC-style atomic typesas instantiations ofatomic). ...
C*expected, C desired); (1)(C11 起) _Bool atomic_compare_exchange_weak(volatileA*obj, C*expected, C desired); (2)(C11 起) _Bool atomic_compare_exchange_strong_explicit(volatileA*obj, C*expected, C desired, memory_ordersucc,
yuncliu changed the title fix atomic operations and spin lock bug in arm64 [arm64 ]fix atomic operations opal_atomic_compare_exchange_strong_ Oct 20, 2023 yuncliu changed the title [arm64 ]fix atomic operations opal_atomic_compare_exchange_strong_ [arm64] fix atomic operations opal_atomic...
C*expected, C desired); (1)(since C11) _Bool atomic_compare_exchange_weak(volatileA*obj, C*expected, C desired); (2)(since C11) _Bool atomic_compare_exchange_strong_explicit(volatileA*obj, C*expected, C desired, memory_ordersucc, ...
in arm64 ldxr and stxr must be used with memory barrier. this cause the spinlock not work in arm64. program may crash or get a wrong result when using multi-thread. Actually we already got both program crash and wrong result of allreduce sum when usi
in arm64 ldxr and stxr must be used with memory barrier. this cause the spinlock not work in arm64. program may crash or get a wrong result when using multi-thread. Actually we already got both...