When I create a instance using a flavor with "hw:cpu_policy=dedicated" "hw:cpu_realtime=yes" and "hw:cpu_realtime_mask=^0-1".

The error is "libvirtError:Cannot set scheduler parameters for pid 3666:operation not permitted".

https://bugs.launchpad.net/starlingx/+bug/1866311

The instance xml as following:

<vcpu placement='static'>4</vcpu>
  <cputune>
    <vcpupin vcpu='0' cpuset='3'/>
    <vcpupin vcpu='1' cpuset='11'/>
    <vcpupin vcpu='2' cpuset='0'/>
    <vcpupin vcpu='3' cpuset='8'/>
    <emulatorpin cpuset='3,11'/>
    <vcpusched vcpus='2' scheduler='fifo' priority='1'/>
    <vcpusched vcpus='3' scheduler='fifo' priority='1'/>
  </cputune>

The error log as following:

 ERROR nova.compute.manager [instance: 74dcc0a1-9ed4-4d13-bef7-ac9623bca2d0] File "/usr/lib64/python2.7/site-packages/libvirt.py", line 1099, in createWithFlags
 ERROR nova.compute.manager [instance: 74dcc0a1-9ed4-4d13-bef7-ac9623bca2d0] if ret == -1: raise libvirtError ('virDomainCreateWithFlags() failed', dom=self)
 ERROR nova.compute.manager [instance: 74dcc0a1-9ed4-4d13-bef7-ac9623bca2d0] libvirtError: Cannot set scheduler parameters for pid 6504: Operation not permitted
 ERROR nova.compute.manager [instance: 74dcc0a1-9ed4-4d13-bef7-ac9623bca2d0]