[cfarm-users] GCC135/Power9 performance?

[Noah Misch]

On Sun, Apr 12, 2020 at 12:03:13AM -0400, Jeffrey Walton via cfarm-users wrote:
> GCC135 is a Power9 machine. Benchmarking on the machine shows
> performance is off. For example, here are some numbers for AES in ECB
> mode:
> 
> GCC112 (Linux, ppc64le, 3.7 GHz, GCC 8.2):
>    * 1.12 cpb, 2851 MB/s
> 
> GCC119 (AIX, ppc64be, 4.1 GHz, GCC 8.2):
>    * 0.54 cpb, 7242 MB/s
> 
> GCC135 (Linux, ppc64le, 3.8 GHz, GCC 8.3):
>    * 1.94 cpb, 1815 MB/s

What source code did you use for this test?

> All algorithms show a similar slowdown. SHA is so slow I am
> considering disabling in-core crypto for SHA and going back to the
> integer unit.
> 
> What is different about GCC135? Is the Power9 hardware really that slow?

Generally no: https://www.ibm.com/downloads/cas/K90RQOW8

Your source code or compiler may tune poorly for POWER9.  I assume you checked
that gcc135 was lightly loaded at the time of your test.