On 2015-06-29 12:11:08 +0200, Andres Freund 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()?
I've pushed a patch the _sched_fence with _mf. That's what we use in the
atomics code as well. I did reread
http://h21007.www2.hp.com/portal/download/files/unprot/Itanium/inline_assem_ERS.pdf
and I do think _Asm_mf is the correct thing.
What I did not change was the mask used for serialization - the default
0x3D3D (c.f. page 23) should be correct, even though slightly
suboptimal.
Andres