Re: Make NUM_XLOGINSERT_LOCKS configurable

Bharath Rupireddy <bharath(dot)rupireddyforpostgres(at)gmail(dot)com> writes:
> On Wed, Jan 10, 2024 at 10:00 AM Tom Lane <tgl(at)sss(dot)pgh(dot)pa(dot)us> wrote:
>> Maybe. I bet just bumping up the constant by 2X or 4X or so would get
>> most of the win for far less work; it's not like adding a few more
>> LWLocks is expensive. But we need some evidence about what to set it to.

> I previously made an attempt to improve WAL insertion performance with
> varying NUM_XLOGINSERT_LOCKS. IIRC, we will lose what we get by
> increasing insertion locks (reduction in WAL insertion lock
> acquisition time) to the CPU overhead of flushing the WAL in
> WaitXLogInsertionsToFinish as referred to by the following comment.

Very interesting --- this is at variance with what the OP said, so
we definitely need details about the test conditions in both cases.

> Unfortunately, I've lost the test results, I'll run them up again and
> come back.

Please.

regards, tom lane