atomic_fetch_{add,sub,inc,dec}{,_relaxed,_acquire,_release}() Bitwise位运算: atomic_{and,or,xor,andnot}() atomic_fetch_{and,or,xor,andnot}{,_relaxed,_acquire,_release}() Swap 交换: atomic_xchg{,_relaxed,_acquire,_release}() atomic_cmpxchg{,_relaxed,_acquire,_release}() atomic_tr...
staticintcas(int*ptr,intcmp,intnew_val){intold_value=*ptr;__asm__volatile("lock; cmpxchg %2, %3":"=a"(old_value),"=m"(*ptr):"r"(new_val),"m"(*ptr),"0"(cmp):"cc","memory");returnold_value;} 直接看汇编十分晦涩,是因为cmpxchg这条指令比较奇怪,有个隐藏的%0参数,假设有三个...
arch_try_cmpxchg_release(__ai_ptr, __ai_oldp, __VA_ARGS__); \ }) #define try_cmpxchg_relaxed(ptr, oldp, ...) \ ({ \ typeof(ptr) __ai_ptr = (ptr); \ typeof(oldp) __ai_oldp = (oldp); \ instrument_atomic_write(__ai_ptr, sizeof(*__ai_ptr)); \ instrument_atom...
while ((old = cmpxchg(&v->counter, c, c c_op i)) != c) \ c = old; \ \ return c; \ } #else #include <linux/irqflags.h> @@ -88,6 +100,20 @@ static inline int atomic_##op##_return(int i, atomic_t *v) \ return ret; \ } #define ATOMIC_FETCH_OP(op, c_op...
这种思想预设所有线程在执行过程中都不会发生冲突，每一个线程都会乐观地认为自己能够成功执行，从而大大...
static inline __int16 __msvc_cmpxchg_i16(__int16 volatile* addr, __int16 oldval, __int16 newval) { return _InterlockedCompareExchange16((__int16 volatile*)addr, newval, oldval); } static inline __int32 __msvc_cmpxchg_i32(__int32 volatile* addr, __int32 oldval, __int...
have better CAS and CMPXCHG performance, a conclusion again largely supported by the data. The db benchmark is an exception, where the largest gain was seen on an older UltraSPARC III system; we believe this may be related to relatively poor associativity of the data cache on this chip. ...
11 @@ #include <cassert> #include <cmpxchg_loop.h> +#include "atomic_helpers.h" template <class T> -void -test() -{ +struct TestFn { + void operator()() const { { typedef std::atomic<T> A; A a; @@ -54,37 +54,10 @@ assert(a == T(2)); assert(t == T(2)); }...
This would be generally followed by a LOCK CMPXCHG to attempt to get the mutex. Failure to obtain the mutex (in a well coded routine) results in a branch to a retry location and thus re-enabling the interrupts. If the mutex is obtained the code falls through thus con...
We got lucky. The compiler was clever enough to see thatTermsfits inside a single 64-bit register, and implementedcompare_exchange_weakusinglock cmpxchg. The compiled code is lock-free. This brings up an interesting point: In general, the C++11 standard doesnotguarantee that atomic operations ...