Re: Improving spin-lock implementation on ARM.

Krunal Bauskar <krunalbauskar@gmail.com> writes:
> Any updates or further inputs on this.

As far as LSE goes: my take is that tampering with the
compiler/platform's default optimization options requires *very*
strong evidence, which we have not got and likely won't get.  Users
who are building for specific hardware can choose to supply custom
CFLAGS, of course.  But we shouldn't presume to do that for them,
because we don't know what they are building for, or with what.

I'm very willing to consider the CAS spinlock patch, but it still
feels like there's not enough evidence to show that it's a universal
win.  The way to move forward on that is to collect more measurements
on additional ARM-based platforms.  And I continue to think that
pgbench is only a very crude tool for testing spinlock performance;
we should look at other tests.

From a system structural standpoint, I seriously dislike that lwlock.c
patch: putting machine-specific variant implementations into that file
seems like a disaster for maintainability.  So it would need to show a
very significant gain across a range of hardware before I'd want to
consider adopting it ... and it has not shown that.

                        regards, tom lane