On 07/11/2013 11:32 PM, Liu Ping Fan wrote: > Refcnt's atomic inc/dec ops are frequent and its idiom need no seq_cst > order. So to get better performance, it worth to adopt _relaxed > other than _seq_cst memory model on them.
You'd need to update the documentation then. As it stands, what you've written looks like a bug. > +#ifndef _GLIBCXX_ATOMIC_BUILTINS This will never be defined. It's private to the libstdc++ implementation. See how we've defined things using __atomic elsewhere in the file, looking at one of the __ATOMIC defines. And in either case, it's better form to use positive tests than negative ones. I.e. #ifdef rather than #ifndef > #define atomic_fetch_inc(ptr) __sync_fetch_and_add(ptr, 1) > #define atomic_fetch_dec(ptr) __sync_fetch_and_add(ptr, -1) I'd prefer atomic_fetch_inc_relaxed, as that's more self-documenting. But I'll re-iterate the necessity of documentation in this area. r~
