Nathan Bossart <nathandboss...@gmail.com> writes: > AFAICT TAS_SPIN() is only used for s_lock(), which doesn't appear to be > used by LWLocks. But I did retry my test from upthread without > pg_stat_statements and was surprised to find a reproducible 4-6% > regression.
On what hardware? I just spent an hour beating on my M4 Pro (the 14-core variant) and could not detect any outside-the-noise effect of this patch, with or without pg_stat_statements loaded. There does seem to be a small fraction-of-a-percent-ish benefit. But the run-to-run variation with 60-second "pgbench -S" tests is a couple of percent, so I can't say that that's real. I do feel pretty sure that the patch doesn't hurt on this class of hardware. regards, tom lane