Andres Freund <andres@anarazel.de> writes:
> On 2019-01-20 10:15:53 -0500, Tom Lane wrote:
>> Indeed, the main reason why I'm interested in keeping this old dinosaur
>> going at all is that it is so different from other platforms in terms
>> of what we can assume about spinlocks and atomic ops. Keeps us honest.
> FWIW, while that clearly is the policy right now, I quite doubt that
> it's beneficial. It's not like there's going to be new hardware
> platforms without at least cmpxchg / ll/sc support. So I'm not seeing
> what not requiring them keeps us honest about.
I think you're being short-sighted. I agree that any reasonable new
hardware platform would have that functionality in some form, but
it won't necessarily be exactly like x86_64 does it. The particular
things I think HPPA is keeping us honest about have to do with the
size of spinlocks and whether they initialize to zero or not.
See e.g. 6b93fcd14 for an actual bug caught by that.
regards, tom lane