Re: LWLock optimization for multicore Power machines

On Mon, Feb 6, 2017 at 8:28 PM, Bernd Helmle <mailings(at)oopsware(dot)de> wrote:

> Am Montag, den 06.02.2017, 16:45 +0300 schrieb Alexander Korotkov:
> > I tried lwlock-power-2.patch on multicore Power machine we have in
> > PostgresPro.
> > I realized that using labels in assembly isn't safe. Thus, I removed
> > labels and use relative jumps instead (lwlock-power-2.patch).
> > Unfortunately, I didn't manage to make any reasonable benchmarks.
> > This
> > machine runs AIX, and there are a lot of problems which prevents
> > PostgreSQL
> > to show high TPS. Installing Linux there is not an option too,
> > because
> > that machine is used for tries to make Postgres work properly on AIX.
> > So, benchmarking help is very relevant. I would very appreciate
> > that.
>
> Okay, so here are some results. The bench runs against
> current PostgreSQL master, 24 GByte shared_buffers configured (128
> GByte physical RAM), max_wal_size=8GB and effective_cache_size=100GB.
>

Thank you very much for testing!

Results looks strange for me. I wonder why there is difference between
lwlock-power-1.patch and lwlock-power-3.patch? From my intuition, it
shouldn't be there because it's not much difference between them. Thus, I
have following questions.

1. Have you warm up database? I.e. could you do "SELECT sum(x.x) FROM
(SELECT pg_prewarm(oid) AS x FROM pg_class WHERE relkind IN ('i', 'r')
ORDER BY oid) x;" before each run?
2. Also could you run each test longer: 3-5 mins, and run them with
variety of clients count?

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