On 2015-06-29 22:11:33 -0400, Robert Haas wrote:
> On Mon, Jun 29, 2015 at 6:11 AM, Andres Freund <andres@anarazel.de> wrote:
> > On 2015-06-29 00:42:53 -0400, Tom Lane wrote:
> >> #define S_UNLOCK(lock) \
> >> do { _Asm_sched_fence(); (*(lock)) = 0; } while (0)
> >
> > Robert, how did you choose that? Isn't _Asm_sched_fence just a compiler
> > barrier? Shouldn't this be a _Asm_mf()?
>
> The point of the commit was to make spinlocks act as compiler barriers
> as well as CPU barriers. So I was just looking to add a compiler
> barrier to what was already there.
You removed a volatile at the same time, and volatile on IA64 has
acquire/release semantics.