[libvirt-users] Question on CPU pinning in Python

[Cole Robinson]

On 09/22/2010 03:51 PM, Stanley, Jon [Tech] wrote:
> Looking at the python API, once I have a domain object I can call domain.pinVcpu to pin a specific vcpu to a physical CPU. I found http://www.mail-archive.com/libvir-list@redhat.com/msg04562.html which mentioned some changes to the C API in the Python implementation, and was wondering if my understanding is correct.
> 
> Say that I have a host system with 16 logical CPU's, 0-15. If I wanted to pin vcpu1 of a domain to CPUs 2 and 4, I would pass:
> 
> domain.pinVcpu(1, (False, False, True, False, True, False....[and so on til I have 16 things]))
> 
> In other words, pinVcpu accepts as arguments the vCPU that I wish to act on, and a 16 (or however many CPU's are present on the host) item tuple of True/False values, in the same order as the CPU's I wish to mask (for example, item 0 of the tuple represents CPU0), True meaning that the vCPU thread is allowed to run there, and False meaning that it is not.
> 
> Just looking to confirm that my understanding of this call is correct.
>

Yes that's correct, we implement this in virt-manager/virtinst. Here's a
function for turning a libvirt cpuset= str into a tuple to pass to pinVcpu:

http://hg.fedorahosted.org/hg/python-virtinst/file/f82c5fcb966a/virtinst/Guest.py#l102

which uses

http://hg.fedorahosted.org/hg/python-virtinst/file/f82c5fcb966a/virtinst/util.py#l264

- Cole