Re: Improving spin-lock implementation on ARM.

Peter Eisentraut <peter.eisentraut@enterprisedb.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