now on Ryzen performance

Erich Dollansky freebsd.ed.lists at
Thu Dec 27 02:53:19 UTC 2018


On Fri, 21 Dec 2018 17:40:49 +0100
Andrea Venturoli <ml at> wrote:

> 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?

I am on FreeBSD 12.0 with a Ryzen 2700X and experience the same
problem. It is a different picture for several ports where really all
cores are used and things get real fast. It seems to be a problem of
the make system as specifying -j 16 leads to errors typically resulting
from build being started while the result required for this start is
not provided by another thread.

Aren't people with real servers using FreeBSD anymore?


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