[Bug 1614054] Re: [SRU] Incorrect host cpu is given to emulator threads when cpu_realtime_mask flag is set

[Łukasz Zemczak]

Thank you for submitting the bug and uploading the fix!

Could we please make sure that the [Impact] field of a bug is used to
nicely outline the impact the bug has on users? Without specific
knowledge of the package itself it's hard for an SRU reviewer to see the
actual impact of the bug and how important the fix is - and these we use
to determine if a fix/change is worth the risk of including it in a
stable release.

For instance here the [Impact] field is completely meaningless (the
title doesn't give too much info for me) - I get some overview when
seeing the patch description in the proposed upload, but this should be
present here. If I would accept it the way it is, another SRU member
that would like to release this change into -updates would have issues
getting an overview of the impact.

Please update the bug description appropriately. The SRU template is
there for something. I know it might sometimes look like that but it's
not just useless paperwork that needs to be copy-pasted blindly.

-- 
You received this bug notification because you are a member of Ubuntu
OpenStack, which is subscribed to Ubuntu Cloud Archive.
https://bugs.launchpad.net/bugs/1614054

Title:
  [SRU] Incorrect host cpu is given to emulator threads when
  cpu_realtime_mask flag is set

Status in Ubuntu Cloud Archive:
  Fix Released
Status in Ubuntu Cloud Archive mitaka series:
  Triaged
Status in OpenStack Compute (nova):
  Fix Released
Status in OpenStack Compute (nova) newton series:
  Fix Committed
Status in nova package in Ubuntu:
  Fix Released
Status in nova source package in Xenial:
  Triaged

Bug description:
  [Impact]

  See bug description

  [Test Case]

   * deploy openstack mitaka and configure nova.conf with vcpu-pin-
  set=0,1,2,3

     https://pastebin.ubuntu.com/25133260/

   * configure compute host kernel opts with "isolcpus=0,1,2,3" + reboot

   * create flavor with:

     openstack flavor create --public --ram 2048 --disk 10 --vcpus 2 --swap 0 test_flavor
     openstack flavor set --property hw:cpu_realtime_mask='^0' test_flavor
     openstack flavor set --property hw:cpu_policy=dedicated test_flavor
     openstack flavor set --property hw:cpu_thread_policy=prefer test_flavor
     openstack flavor set --property hw:cpu_realtime=yes test_flavor

   * boot instance with ^^ flavor

   * check that libvirt xml for vm has correct emulator pin cpuset #

  [Regression Potential]

  None expected.

  
  ====

  Description of problem:
  When using the cpu_realtime and cpu_realtim_mask flag to create new instance, the 'cpuset' of 'emulatorpin' option is using the id of vcpu which is incorrect. The id of host cpu should be used here.

  e.g.
    <cputune>
      <vcpupin vcpu='0' cpuset='2'/>
      <vcpupin vcpu='1' cpuset='3'/>
      <emulatorpin cpuset='0'/>          ### the cpuset should be '2' here, when cpu_realtime_mask=^0.
      <vcpusched vcpus='1' scheduler='fifo' priority='1'/>
    </cputune>

  How reproducible:
  Boot new instance with cpu_realtime_mask flavor.

  Steps to Reproduce:
  1. Create RT flavor
  nova flavor-create m1.small.performance 6 2048 20 2
  nova flavor-key m1.small.performance set hw:cpu_realtime=yes
  nova flavor-key m1.small.performance set hw:cpu_realtime_mask=^0
  nova flavor-key m1.small.performance set hw:cpu_policy=dedicated
  2. Boot a instance with this flavor
  3. Check the xml of the new instance

  Actual results:
    <cputune>
      <vcpupin vcpu='0' cpuset='2'/>
      <vcpupin vcpu='1' cpuset='3'/>
      <emulatorpin cpuset='0'/>
      <vcpusched vcpus='1' scheduler='fifo' priority='1'/>
    </cputune>

  Expected results:
    <cputune>
      <vcpupin vcpu='0' cpuset='2'/>
      <vcpupin vcpu='1' cpuset='3'/>
      <emulatorpin cpuset='2'/>
      <vcpusched vcpus='1' scheduler='fifo' priority='1'/>
    </cputune>

To manage notifications about this bug go to:
https://bugs.launchpad.net/cloud-archive/+bug/1614054/+subscriptions