[vfio-users] Advice on cpu pinning AMD FX 8350

[David Sutton]

Alex,

On Sun, Aug 30, 2015 at 5:16 PM, Alex Williamson <
alex.l.williamson at gmail.com> wrote:

> On Sun, Aug 30, 2015 at 4:08 PM, David Sutton <kantras at gmail.com> wrote:
>
>> Hi there,
>>
>> On Sat, Aug 29, 2015 at 8:00 PM, Blank Field <ihatethisfield at gmail.com>
>> wrote:
>>
>>> Everything as usual. By usual i mean i7 hyperthreaded cores.
>>> Pair siblings cores.
>>> Those, who share the FPU, and, AFAIR, caches.
>>> To know your exact logical CPU numbers you should examine /proc/cpuinfo
>>> closely.
>>>
>>>
>>   I was aware of the core/module pairings, so /proc/cpuinfo was one of
>> the first places that I had looked for clues; the problem is that I don't
>> see it showing anywhere obvious about how the core/module pairing is
>> numbered (ie 0-1,2-3,4-5,6-7 or 0-4,1-5,2-6,3-7)
>>
>
> You can try my script that uses netperf to determine core-to-core
> latencies to figure out whether cores are paired:
>
> https://github.com/awilliam/cpu-latencies
>
> Hopefully you'll at most need to change the path to netperf and netserver
> and have taskset and bc installed.  Give it a try.
>

Thanks for the advice - your script worked well:

The output I got was:

 |  0  1  2  3  4  5  6  7
--+------------------------
0| 10  8  7  7  7  7  7  7
1|  8 10  7  7  7  7  7  7
2|  7  7 10  8  7  7  7  7
3|  7  7  8 10  7  7  7  7
4|  7  7  7  7 10  8  7  7
5|  7  7  7  7  8 10  7  7
6|  7  7  7  7  7  7 10  8
7|  7  7  7  7  7  7  8 10

So it appears that it is 0-1,2-3,4-5 and 6-7.

Regards,

  David
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