Re: Should we cacheline align PGXACT?

Hi, Tomas!

On Sat, Feb 11, 2017 at 2:28 AM, Tomas Vondra <tomas(dot)vondra(at)2ndquadrant(dot)com>
wrote:

> As discussed at the Developer meeting ~ a week ago, I've ran a number of
> benchmarks on the commit, on a small/medium-size x86 machines. I currently
> don't have access to a machine as big as used by Alexander (with 72
> physical cores), but it seems useful to verify the patch does not have
> negative impact on smaller machines.
>
> In particular I've ran these tests:
>
> * r/o pgbench
> * r/w pgbench
> * 90% reads, 10% writes
> * pgbench with skewed distribution
> * pgbench with skewed distribution and skipping
>

Thank you very much for your efforts!
I took a look at these tests. One thing catch my eyes. You warmup
database using pgbench run. Did you consider using pg_prewarm instead?

SELECT sum(x.x) FROM (SELECT pg_prewarm(oid) AS x FROM pg_class WHERE
relkind IN ('i', 'r') ORDER BY oid) x;

In my experience pg_prewarm both takes less time and leaves less variation
afterwards.

------
Alexander Korotkov
Postgres Professional: http://www.postgrespro.com
The Russian Postgres Company