Re: Make NUM_XLOGINSERT_LOCKS configurable

<1111hqshj(at)sina(dot)com> writes:
> I recently used benchmarksql to evaluate the performance of postgresql. I achieved nearly 20% improvement
> with NUM_XLOGINSERT_LOCKS changed from 8 to 16 under some cases of high concurrency. I wonder whether
> it is feasible to make NUM_XLOGINSERT_LOCKS a configuration parameter, so that users can get easier to optimize
> their postgresql performance through this setting.

Making it an actual GUC would carry nontrivial costs, not least that
there are hot code paths that do "foo % NUM_XLOGINSERT_LOCKS" which
would go from a mask operation to a full integer divide. We are
unlikely to consider that on the basis of an unsupported assertion
that there's a performance gain under unspecified conditions.

Even with data to justify a change, I think it'd make a lot more sense
to just raise the constant value.

regards, tom lane