Re: Some performance degradation in REL_16 vs REL_15

Hi,

On 2023-10-12 11:00:22 +0300, Anton A. Melnikov wrote:
> Found that simple test pgbench -c20 -T20 -j8 gives approximately
> for REL_15_STABLE at 5143f76:  336+-1 TPS
> and
> for REL_16_STABLE at 4ac7635f: 324+-1 TPS
> 
> The performance drop is approximately 3,5%  while the corrected standard deviation is only 0.3%.
> See the raw_data.txt attached.

Could you provide a bit more details about how you ran the benchmark?  The
reason I am asking is that ~330 TPS is pretty slow for -c20.  Even on spinning
rust and using the default settings, I get considerably higher results.

Oh - I do get results closer to yours if I use pgbench scale 1, causing a lot
of row level contention. What scale did you use?

Greetings,

Andres Freund