Il 19/06/2013 22:44, Richard Henderson ha scritto: >>> >> + /* Data must be read atomically. We don't really need barrier >>> >> semantics >>> >> + * but it's easier to use atomic_* than roll our own. */ >>> >> + log = atomic_xchg(from, 0); >> > >> > If you really don't need any ordering guarantees / barriers here, then >> > using a relaxed load should be fine. But my gut feeling tells me you >> > probably do need some barriers; either you are "re-using" another >> > barrier (and then the comment should probably point out which), or it >> > must be a case where it's either fine to read any value someone (else) >> > wrote or there's no concurrent store after all. >> > > There is a store here, before and after. Read the value, store zero. > > I suppose what the comment is saying is that the atomic operation doesn't need > to be ordered with respect to the rest of the surrounding code, as the object > being synchronized is just that one integer.
Exactly. The items of the array can be read independently. Paolo
