now on Ryzen performance

Andrea Venturoli ml at
Fri Dec 21 16:41:03 UTC 2018

On 12/21/18 10:27 AM, Andrea Venturoli wrote:
> On 12/4/18 12:21 PM, Erich Dollansky wrote:
>> I just followed this mailing list and read some random articles. There
>> seem to be no real stability problems which cannot be explained by other
>> things like faulty motherboards etc.
> Hello.
> Just in case it helps others, I think I can conclude my new Ryzen 7 
> system works fine: uptime is almost a week, with high and low load 
> cycles (some idle time, some Poudriere, some server work, etc...).
> I'm still running 11.2, BTW.

Hello again.

Now that I verified this system stability, I moved into measuring its 
performance and I think something is wrong here.

A buildworld took many hours more than on any other system I'm managing 
(some even quite old), so I concluded some more investigation was needed.
So I compared it to a (software-wise identical) system with a (7 year 
old) AMD Phenom II X4 965 (just because this was the CPU I had more 
easily available).

According to UserBenchmark, a Ryzen 2700 should be 74% faster at single 
threading: if I interpret this correctly, it means total execution time 
should be 43% less...
However, "time some_intensive_single_thread_task" showed the Ryzen 
completing the same work in 24% more time!!!

Going to four threads (which is the maximum available on the Phenom) 
shows the same results.
Of course using all 8 cores on the Ryzen takes 26% less time than using 
4 on the Phenom, but that's not the point (and it's still slow).
I have disabled SMT in the BIOS, so I didn't try with 16 threads.

Having powerd running or not does not make any difference.

When running "powerd -v" I see the Ryzen always working at 3.2GHz, which 
it's its base speed. It doesn't seem to use its "Max Boost Clock"  of 
4.1GHz. Is this to be expected? Is this feature only available in 12.0?

Then again, if it just scaled linearly between the two frequencies it 
would still be much slower than I expected...

Any hint?
Is moving to 12 going to change this?

  bye & Thanks

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