[openstack-dev] realtime kvm cpu affinities

Chris Friesen chris.friesen at windriver.com
Tue Jun 27 16:16:23 UTC 2017

On 06/27/2017 09:36 AM, Henning Schild wrote:
> Am Tue, 27 Jun 2017 09:28:34 -0600
> schrieb Chris Friesen <chris.friesen at windriver.com>:

>> Once you use "isolcpus" on the host, the host scheduler won't "float"
>> threads between the CPUs based on load.  To get the float behaviour
>> you'd have to not isolate the pCPUs that will be used for emulator
>> threads, but then you run the risk of the host running other work on
>> those pCPUs (unless you use cpusets or something to isolate the host
>> work to a subset of non-isolcpus pCPUs).
> With openstack you use libvirt and libvirt uses cgroups/cpusets to get
> those threads onto these cores.

Right.  I misremembered.  We are currently using "isolcpus" on the compute node 
to isolate the pCPUs used for packet processing, but the pCPUs used for guests 
are not isolated.


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