Re: [HACKERS] Deadlock in XLogInsert at AIX

Am Dienstag, den 16.01.2018, 08:25 +0000 schrieb REIX, Tony:
> I've been able to compare PostgreSQL compiled with XLC vs GCC 7.1
> and, using times outputs provided by PostgreSQL tests, XLC seems to
> provide at least 8% more speed. We also plan to run professional
> performance tests in order to compare PostgreSQL 10.1 on AIX vs
> Linux/Power. I saw some 2017 performance slides, made with older
> versions of PostgreSQL and XLC, that show bad PostgreSQL performance
> on AIX vs Linux/Power, and I cannot believe it. We plan to
> investigate this.

I assume you are referring to the attached graph i've showed on
PGConf.US 2017 ?

The numbers we've got on that E850 machine (pgbench SELECT-only, scale
1000) weren't really good in comparison to Linux on the same machine.

We tried many options to make the performance better, overall the graph
shows the best performance from Linux *and* AIX with gcc. XL C We used
some knobs to get the best out on AIX:

export OBJECT_MODE=64; gcc -m64
ldedit -b forkpolicy:cor -b textpsize:64K -b datapsize:64K -b
stackpsize:64K postgres
export MALLOCOPTIONS=multiheap:16,considersize,pool,no_mallinfo
schedo -p -o vpm_fold_policy=4

There are many other things you can tune on AIX, but they didn't seem
to give the improvement we'd like to see.