Ryzen issues on FreeBSD ?

[Don Lewis]

On 21 Jan, Willem Jan Withagen wrote:
> On 21/01/2018 21:24, Don Lewis wrote:
>> On 21 Jan, Willem Jan Withagen wrote:
>>> On 19/01/2018 23:29, Don Lewis wrote:
>>>> On 19 Jan, Pete French wrote:
>>>>> Out of interest, is there anyone out there running Ryzen who *hasnt*
>>>>> seen lockups ? I'd be curious if there a lot of lurkers thinking "mine
>>>>> works fine"
>>>>
>>>> No hangs or silent reboots here with either my original CPU or warranty
>>>> replacement once the shared page fix was in place.
>>>
>>> Perhaps a too weird reference:
>>>
>>> I have supplied a customer with a Ryzen5 and a 350MB motherboard.
>>> But he runs Windows 10, but I haven't heard him complain about anything
>>> like this.
>>> But I'll ask him specific.
>> 
>> Only the BSDs were affected by the shared page issue.  I think Linux
>> already had a guard page.  I don't think Windows was affected by the
>> idle C-state issue.  I suspect it is caused by software not doing the
>> right thing during C-state transitions, but the publicly available
>> documentation from AMD is pretty lacking.  The random segfault issue is
>> primarily triggered by heavy parallel software build loads and how many
>> Windows users do that?
> 
> This is an adobe workstation where several users remote login and do 
> work. So I would assume that the system is seriously (ab)used.
> 
> Adn as expected I'm know aware of any of the detailed things that 
> Windows does while powering into lesser active states.

It might depend on the scheduler details.  On Linux and the FreeBSD ULE
scheduler, runnable threads migrate between CPUs to balance the loading
across all cores.  When I did some experiments to disable that, the rate
of build failures greatly decreased.  AMD has been very vague about the
cause of the problem (a "performance marginality") and resorted to
replacing CPUs with this problem without suggesting any sort of software
workaround.