Ryzen issues on FreeBSD ?

[Don Lewis]

On 27 Jan, Mike Tancsa wrote:
> On 1/27/2018 3:23 AM, Don Lewis wrote:
>> 
>> I just ran into this for this first time with samba46.  I kicked of a
>> ports build this evening before leaving for several hours.  When I
>> returned, samba46 had failed with a build runaway.  I just tried again
>> and I see python stuck in the usem state.  This is what I see with
>> procstat -k:
> 
> Hmmm, is this indicative of a processor bug or a FreeBSD bug or its
> indeterminate at this point ?

My suspicion is a FreeBSD bug, probably a locking / race issue.  I know
that we've had to make some tweeks to our code for AMD CPUs, like this:

------------------------------------------------------------------------
r321608 | kib | 2017-07-27 01:37:07 -0700 (Thu, 27 Jul 2017) | 9 lines

Use MFENCE to serialize RDTSC on non-Intel CPUs.

Kernel already used the stronger barrier instruction for AMDs, correct
the userspace fast gettimeofday() implementation as well.



I did go back and look at the build runaways that I've occasionally seen
on my AMD FX-8320E package builder.  I haven't seen the python issue
there, but have seen gmake get stuck in a sleeping state with a bunch of
zombie offspring.