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...
cmpxchg指令 前一阵十分流行的无锁编程,让我们眼前比较明亮,很多人认为无锁编程的主要原因就是因为CPU支持了cmpxchg这个指令,网上很多人都说cmpxchg这个指令是原子指令,其实这个说明是错误的,cmpxchg这个指令并不是原子指令,只是CPU支持了一个新的指令 大家可以看一下操作系统内核实现的这个函数: cmpxchg函数 #define __...
atomic_long_fetch_##op##mo(long i, atomic_long_t *l) \ { \ ATOMIC_LONG_PFX(_t) *v = (ATOMIC_LONG_PFX(_t) *)l; \ \ return (long)ATOMIC_LONG_PFX(_fetch_##op##mo)(i, v); \ } ATOMIC_LONG_FETCH_OP(add, ) ATOMIC_LONG_FETCH_OP(add, _relaxed) ATOMIC_LONG_FETCH_OP...
arch_try_cmpxchg_relaxed(__ai_ptr, __ai_oldp, __VA_ARGS__); \ }) @@ -2077,17 +2077,17 @@ atomic_long_dec_if_positive(atomic_long_t *v) typeof(ptr) __ai_ptr = (ptr); \ typeof(oldp) __ai_oldp = (oldp); \ kcsan_mb(); \ instrument_atomic_write(__ai_ptr, size...
#define ATOMIC_LONG_LOCK_FREE 1 #define ATOMIC_LLONG_LOCK_FREE 1 #define ATOMIC_POINTER_LOCK_FREE 1 #define ATOMIC_FLAG_INIT { 0 } #define __ATOMIC_RELAXED 0 #define __ATOMIC_CONSUME 1 #define __ATOMIC_ACQUIRE 2 #define __ATOMIC_RELEASE 3 #define __ATOMIC_ACQ_REL 4 ...
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. ...
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...
11 @@ #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; @@ -61,37 +62,10 @@ assert(a == T(2)); assert(t == T(2)); } -} - -struct ...
10 @@ #include <cmpxchg_loop.h> +#include "atomic_helpers.h" + template <class T> -void -test() +void test() { { typedef std::atomic<T> A; @@ -63,35 +64,7 @@ } } -struct A -{ - int i; - - explicit A(int d = 0) noexcept {i=d;} - - friend bool operator==...
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...