Re: Improving spin-lock implementation on ARM.

Peter Eisentraut <peter(dot)eisentraut(at)enterprisedb(dot)com> writes:
> I tried this on a M1 MacBook Air. I cannot reproduce these results.
> The unpatched numbers are about in the neighborhood of what you showed,
> but the patched numbers are only about a few percent better, not the
> 1.5x or 2x change that you showed.

After redoing the test, I can't find any outside-the-noise difference
at all between HEAD and the patch. So clearly, I screwed up yesterday.
The most likely theory is that I managed to measure an assert-enabled
build of HEAD.

It might be that this hardware is capable of showing a difference with a
better-tuned pgbench test, but with an untuned pgbench run, we just aren't
sufficiently sensitive to the spinlock properties. (Which I guess is good
news, really.)

One thing that did hold up is that the thermal performance of this box
is pretty ridiculous. After being beat on for a solid hour, the fan
still hasn't turned on to any noticeable level, and the enclosure is
only a little warm to the touch. Try that with Intel hardware ;-)

regards, tom lane