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Bug 1170492 - ignore emulatorpin when vcpu placement is auto
Summary: ignore emulatorpin when vcpu placement is auto
Keywords:
Status: CLOSED ERRATA
Alias: None
Product: Red Hat Enterprise Linux 7
Classification: Red Hat
Component: libvirt
Version: 7.1
Hardware: x86_64
OS: Linux
medium
medium
Target Milestone: rc
: ---
Assignee: Michal Privoznik
QA Contact: Virtualization Bugs
URL:
Whiteboard:
Depends On: 1170484
Blocks: 1170495
TreeView+ depends on / blocked
 
Reported: 2014-12-04 06:45 UTC by Jincheng Miao
Modified: 2015-11-19 05:57 UTC (History)
6 users (show)

Fixed In Version: libvirt-1.2.13-1.el7
Doc Type: Bug Fix
Doc Text:
Clone Of:
: 1170495 (view as bug list)
Environment:
Last Closed: 2015-11-19 05:57:08 UTC
Target Upstream Version:
Embargoed:

Attachments (Terms of Use)


Links
System ID Private Priority Status Summary Last Updated
Red Hat Product Errata RHBA-2015:2202 0 normal SHIPPED_LIVE libvirt bug fix and enhancement update 2015-11-19 08:17:58 UTC

Description Jincheng Miao 2014-12-04 06:45:54 UTC 
Description of problem:
vcpu placement is default to numatune placement or "static" if cpuset is specified.
So if user edit domain xml as:
  <vcpu placement='static' current='2'>6</vcpu>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

libvirt will turn vcpu placement to 'auto', like:
  <vcpu placement='auto' current='2'>6</vcpu>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

But this tuning will break the rule of emulatorpin is not allowed if attribute placement of element vcpu is "auto".

In other word, emulatorpin could be set when vcpu placement is 'static', and numatune memory placement is 'auto':
  <vcpu placement='auto' current='2'>6</vcpu>
  <cputune>
    <emulatorpin cpuset='1-3'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>



Version-Release number of selected component (if applicable):
libvirt-1.2.8-9.el7.x86_64
qemu-kvm-rhev-2.1.2-13.el7.x86_64

How reproducible:
100%

Steps to Reproduce:
1. edit domain xml
# virsh edit r7a
...
  <vcpu placement='static' current='2'>6</vcpu>
  <cputune>
    <emulatorpin cpuset='1-3'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

...

# virsh dumpxml r7a
...
  <vcpu placement='auto' current='2'>6</vcpu>
  <cputune>
    <emulatorpin cpuset='1-3'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>
...

2. start guest
# virsh start r7a

3. check via emulatorpin
# virsh emulatorpin r7a
emulator: CPU Affinity
----------------------------------
       *: 1-3

4. check via cgroup
# cat /sys/fs/cgroup/cpuset/machine.slice/machine-qemu\\x2dr7a.scope/emulator/cpuset.cpus
0-7


Expect result:
Either report error for specifying emulatorpin when vcpu placement is auto,
or ignoring emulatorpin configuration.
Comment 1 Jincheng Miao 2014-12-04 07:06:05 UTC 
This problem is also existing for iothreadpin of cputune.

And It's also existed in RHEL6, I will clone it to RHEL6.
Comment 2 Michal Privoznik 2015-01-22 13:09:28 UTC 
Patch proposed upstream:

https://www.redhat.com/archives/libvir-list/2015-January/msg00845.html
Comment 3 Michal Privoznik 2015-01-30 13:02:44 UTC 
I've just pushed the patch upstream:

commit bbd3eb50987676f486effe55feec1fe0d01cafd0
Author:     Michal Privoznik <mprivozn>
AuthorDate: Thu Jan 22 13:57:22 2015 +0100
Commit:     Michal Privoznik <mprivozn>
CommitDate: Fri Jan 30 13:51:22 2015 +0100

    conf: Don't mangle vcpu placement randomly
    
    https://bugzilla.redhat.com/show_bug.cgi?id=1170492
    
    In one of our previous commits (dc8b7ce7) we've done a functional
    change even though it was intended as pure refactor. The problem is,
    that the following XML:
    
     <vcpu placement='static' current='2'>6</vcpu>
     <cputune>
       <emulatorpin cpuset='1-3'/>
     </cputune>
     <numatune>
       <memory mode='strict' placement='auto'/>
     </numatune>
    
    gets translated into this one:
    
     <vcpu placement='auto' current='2'>6</vcpu>
     <cputune>
       <emulatorpin cpuset='1-3'/>
     </cputune>
     <numatune>
       <memory mode='strict' placement='auto'/>
     </numatune>
    
    We should not change the vcpu placement mode. Moreover, we're doing
    something similar in case of emulatorpin and iothreadpin. If they were
    set, but vcpu placement was auto, we've mistakenly removed them from
    the domain XML even though we are able to set them independently on
    vcpus.
    
    Signed-off-by: Michal Privoznik <mprivozn>

v1.2.12-50-gbbd3eb5
Comment 6 Luyao Huang 2015-06-25 06:53:58 UTC 
I can reproduce this issue with libvirt-1.2.8-16.el7.x86_64:

1. edit xml like this:

  <vcpu placement='static'>5</vcpu>
  <iothreads>2</iothreads>
  <cputune>
    <vcpupin vcpu='2' cpuset='1'/>
     <emulatorpin  cpuset='1'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

2. recheck the xml after edit:

# virsh dumpxml test4

  <vcpu placement='auto'>5</vcpu>
  <iothreads>2</iothreads>
  <cputune>
    <vcpupin vcpu='2' cpuset='1'/>
    <emulatorpin cpuset='1'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

And verify this issue with libvirt-1.2.16-1.el7.x86_64:

1. edit xml like this:

  <vcpu placement='static'>5</vcpu>
  <iothreads>2</iothreads>
  <cputune>
    <vcpupin vcpu='2' cpuset='1'/>
    <emulatorpin cpuset='2'/>
    <iothreadpin iothread='1' cpuset='3'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

2. recheck the xml after edit:

# virsh dumpxml test4

  <vcpu placement='static'>5</vcpu>
  <iothreads>2</iothreads>
  <cputune>
    <vcpupin vcpu='2' cpuset='1'/>
    <emulatorpin cpuset='2'/>
    <iothreadpin iothread='1' cpuset='3'/>
  </cputune>
  <numatune>
    <memory mode='strict' placement='auto'/>
  </numatune>

3. start the guest and check the cgroup:

# cgget -g cpuset /machine.slice/machine-qemu\\x2dtest4.scope/iothread1
/machine.slice/machine-qemu\x2dtest4.scope/iothread1:
cpuset.isolcpus: 3
cpuset.memory_spread_slab: 0
cpuset.memory_spread_page: 0
cpuset.memory_pressure: 0
cpuset.memory_migrate: 1
cpuset.sched_relax_domain_level: -1
cpuset.sched_load_balance: 1
cpuset.mem_hardwall: 0
cpuset.mem_exclusive: 0
cpuset.cpu_exclusive: 0
cpuset.mems: 0
cpuset.cpus: 3

# cgget -g cpuset /machine.slice/machine-qemu\\x2dtest4.scope/emulator
/machine.slice/machine-qemu\x2dtest4.scope/emulator:
cpuset.isolcpus: 2
cpuset.memory_spread_slab: 0
cpuset.memory_spread_page: 0
cpuset.memory_pressure: 0
cpuset.memory_migrate: 1
cpuset.sched_relax_domain_level: -1
cpuset.sched_load_balance: 1
cpuset.mem_hardwall: 0
cpuset.mem_exclusive: 0
cpuset.cpu_exclusive: 0
cpuset.mems: 0
cpuset.cpus: 2

# cgget -g cpuset /machine.slice/machine-qemu\\x2dtest4.scope/vcpu2
/machine.slice/machine-qemu\x2dtest4.scope/vcpu2:
cpuset.isolcpus: 
cpuset.memory_spread_slab: 0
cpuset.memory_spread_page: 0
cpuset.memory_pressure: 0
cpuset.memory_migrate: 1
cpuset.sched_relax_domain_level: -1
cpuset.sched_load_balance: 1
cpuset.mem_hardwall: 0
cpuset.mem_exclusive: 0
cpuset.cpu_exclusive: 0
cpuset.mems: 0
cpuset.cpus: 1
Comment 8 errata-xmlrpc 2015-11-19 05:57:08 UTC 
Since the problem described in this bug report should be
resolved in a recent advisory, it has been closed with a
resolution of ERRATA.

For information on the advisory, and where to find the updated
files, follow the link below.

If the solution does not work for you, open a new bug report.

https://rhn.redhat.com/errata/RHBA-2015-2202.html
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