No, There is no changes made in kernel.
My flavor has currently below specs set.
| dec2e31d-e1e8-4ff2-90d5-955be7e9efd3 | RC-16G         | 16384 |    5 |         0 |     8 | True      |    0 |         1.0 | hw:cpu_cores='2', hw:cpu_sockets='4'              |

But I have set cpu pinning in compute node.
[compute]
cpu_shared_set = 2-7,10-15,18-23,26-31

If I remove hw:cpu_* from flavor and remove above config from nova.conf of compute. Instance deployment works fine.

You seem to have 4 NUMA as well, but only two physical sockets (8CPUx2threads - 16 vCPUs per socket x 2 = 32)

This is my test compute node have 4 cpu sockets and 4 numa nodes.

root@kvm10-a1-khi01:~# numactl -H
available: 4 nodes (0-3)
node 0 cpus: 0 1 2 3 4 5 6 7
node 0 size: 31675 MB
node 0 free: 30135 MB
node 1 cpus: 8 9 10 11 12 13 14 15
node 1 size: 64510 MB
node 1 free: 63412 MB
node 2 cpus: 16 17 18 19 20 21 22 23
node 2 size: 64510 MB
node 2 free: 63255 MB
node 3 cpus: 24 25 26 27 28 29 30 31
node 3 size: 64485 MB
node 3 free: 63117 MB
node distances:
node   0   1   2   3
  0:  10  16  16  16
  1:  16  10  16  16
  2:  16  16  10  16
  3:  16  16  16  10 

The generated XML seems to be set for a 4 socket topology?

Yes I am testing this on my test compute node first.

On Wed, Jun 30, 2021 at 7:15 AM Laurent Dumont <laurentfdumont@gmail.com> wrote:
  • Is there any isolation done at the Kernel level of the compute OS?
  • What does your flavor look like right now? Is the behavior different if you remove the numa constraint?
You seem to have 4 NUMA as well, but only two physical sockets (8CPUx2threads - 16 vCPUs per socket x 2 = 32)

The generated XML seems to be set for a 4 socket topology?

 <cpu mode='custom' match='exact' check='partial'>
    <model fallback='allow'>Opteron_G5</model>
    <topology sockets='4' cores='2' threads='1'/>
  </cpu>

On Tue, Jun 29, 2021 at 12:41 PM Ammad Syed <syedammad83@gmail.com> wrote:
Hi Stephen,

I have checked all cpus are online.

root@kvm10-a1-khi01:/etc/nova# lscpu
Architecture:                    x86_64
CPU op-mode(s):                  32-bit, 64-bit
Byte Order:                      Little Endian
Address sizes:                   48 bits physical, 48 bits virtual
CPU(s):                          32
On-line CPU(s) list:             0-31
Thread(s) per core:              2
Core(s) per socket:              8
Socket(s):                       2
NUMA node(s):                    4
Vendor ID:                       AuthenticAMD
CPU family:                      21

I have made below configuration in nova.conf.

[compute]

cpu_shared_set = 2-7,10-15,18-23,26-31

Below is the xml in nova logs that nova is trying to create domain.

2021-06-29 16:30:56.576 2819 ERROR nova.virt.libvirt.guest [req-c76c6809-1775-43a8-bfb1-70f6726cad9d 2af528fdf3244e15b4f3f8fcfc0889c5 890eb2b7d1b8488aa88de7c34d08817a - default default] Error launching a defined domain with XML: <domain type='kvm'>
  <name>instance-0000026d</name>
  <uuid>06ff4fd5-b21f-4f64-9dde-55e86dd15da6</uuid>
  <metadata>
    <nova:instance xmlns:nova="http://openstack.org/xmlns/libvirt/nova/1.1">
      <nova:package version="23.0.0"/>
      <nova:name>cpu</nova:name>
      <nova:creationTime>2021-06-29 16:30:50</nova:creationTime>
      <nova:flavor name="RC-16G">
        <nova:memory>16384</nova:memory>
        <nova:disk>5</nova:disk>
        <nova:swap>0</nova:swap>
        <nova:ephemeral>0</nova:ephemeral>
        <nova:vcpus>8</nova:vcpus>
      </nova:flavor>
      <nova:owner>
        <nova:user uuid="2af528fdf3244e15b4f3f8fcfc0889c5">admin</nova:user>
        <nova:project uuid="890eb2b7d1b8488aa88de7c34d08817a">admin</nova:project>
      </nova:owner>
      <nova:root type="image" uuid="1024317b-0db6-418c-bc39-de9b61d8ce59"/>
      <nova:ports>
        <nova:port uuid="dccf68a2-ec48-4985-94ce-b3487cfc99f3">
          <nova:ip type="fixed" address="192.168.100.106" ipVersion="4"/>
        </nova:port>
      </nova:ports>
    </nova:instance>
  </metadata>
  <memory unit='KiB'>16777216</memory>
  <currentMemory unit='KiB'>16777216</currentMemory>
  <vcpu placement='static' cpuset='2-7,10-15,18-23,26-31'>8</vcpu>
  <cputune>
    <shares>8192</shares>
  </cputune>
  <sysinfo type='smbios'>
    <system>
      <entry name='manufacturer'>OpenStack Foundation</entry>
      <entry name='product'>OpenStack Nova</entry>
      <entry name='version'>23.0.0</entry>
      <entry name='serial'>06ff4fd5-b21f-4f64-9dde-55e86dd15da6</entry>
      <entry name='uuid'>06ff4fd5-b21f-4f64-9dde-55e86dd15da6</entry>
      <entry name='family'>Virtual Machine</entry>
    </system>
  </sysinfo>
  <os>
    <type arch='x86_64' machine='pc-i440fx-4.2'>hvm</type>
    <boot dev='hd'/>
    <smbios mode='sysinfo'/>
  </os>
  <features>
    <acpi/>
    <apic/>
  </features>
  <cpu mode='custom' match='exact' check='partial'>
    <model fallback='allow'>Opteron_G5</model>
    <topology sockets='4' cores='2' threads='1'/>
  </cpu>
  <clock offset='utc'>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='hpet' present='no'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <devices>
    <emulator>/usr/bin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2' cache='none'/>
      <source file='/var/lib/nova/instances/06ff4fd5-b21f-4f64-9dde-55e86dd15da6/disk'/>
      <target dev='sda' bus='scsi'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <controller type='scsi' index='0' model='virtio-scsi'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </controller>
    <controller type='usb' index='0' model='piix3-uhci'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <interface type='bridge'>
      <mac address='fa:16:3e:f5:46:7d'/>
      <source bridge='br-int'/>
      <virtualport type='openvswitch'>
        <parameters interfaceid='dccf68a2-ec48-4985-94ce-b3487cfc99f3'/>
      </virtualport>
      <target dev='tapdccf68a2-ec'/>
      <model type='virtio'/>
      <driver name='vhost' queues='8'/>
      <mtu size='1442'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <log file='/var/lib/nova/instances/06ff4fd5-b21f-4f64-9dde-55e86dd15da6/console.log' append='off'/>
      <target type='isa-serial' port='0'>
        <model name='isa-serial'/>
      </target>
    </serial>
    <console type='pty'>
      <log file='/var/lib/nova/instances/06ff4fd5-b21f-4f64-9dde-55e86dd15da6/console.log' append='off'/>
      <target type='serial' port='0'/>
    </console>
    <input type='tablet' bus='usb'>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes' listen='0.0.0.0'>
      <listen type='address' address='0.0.0.0'/>
    </graphics>
    <video>
      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <memballoon model='virtio'>
      <stats period='10'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0'/>
    </memballoon>
    <rng model='virtio'>
      <backend model='random'>/dev/urandom</backend>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </rng>
  </devices>
</domain>
: libvirt.libvirtError: Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000026d.scope/emulator/cpuset.cpus': Permission denied

Ammad

On Tue, Jun 29, 2021 at 8:29 PM Stephen Finucane <stephenfin@redhat.com> wrote:
On Tue, 2021-06-29 at 17:44 +0500, Ammad Syed wrote:
> Thanks,, the information is really helpful. I am have set below properties to
> flavor according to my numa policies. 
>
>     --property hw:numa_nodes=FLAVOR-NODES \
>     --property hw:numa_cpus.N=FLAVOR-CORES \
>     --property hw:numa_mem.N=FLAVOR-MEMORY
>
> I am having below error in compute logs. Any advise.
>
>  libvirt.libvirtError: Unable to write to
> '/sys/fs/cgroup/cpuset/machine.slice/machine-
> qemu\x2d48\x2dinstance\x2d0000026b.scope/emulator/cpuset.cpus': Permission
> denied
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest Traceback (most
> recent call last):
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/nova/virt/libvirt/guest.py", line 155, in launch
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     return
> self._domain.createWithFlags(flags)
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 193, in doit
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     result =
> proxy_call(self._autowrap, f, *args, **kwargs)
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 151, in proxy_call
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     rv =
> execute(f, *args, **kwargs)
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 132, in execute
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     six.reraise(c,
> e, tb)
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/six.py", line 703, in reraise
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     raise value
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/eventlet/tpool.py", line 86, in tworker
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     rv =
> meth(*args, **kwargs)
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest   File
> "/usr/lib/python3/dist-packages/libvirt.py", line 1265, in createWithFlags
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest     if ret == -1:
> raise libvirtError ('virDomainCreateWithFlags() failed', dom=self)
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest
> libvirt.libvirtError: Unable to write to
> '/sys/fs/cgroup/cpuset/machine.slice/machine-
> qemu\x2d48\x2dinstance\x2d0000026b.scope/emulator/cpuset.cpus': Permission
> denied
> 2021-06-29 12:33:10.144 1310945 ERROR nova.virt.libvirt.guest
> 2021-06-29 12:33:10.146 1310945 ERROR nova.virt.libvirt.driver [req-4f6fc6aa-
> 04d6-4dc0-921f-2913b40a76a9 2af528fdf3244e15b4f3f8fcfc0889c5
> 890eb2b7d1b8488aa88de7c34d08817a - default default] [instance: ed87bf68-b631-
> 4a00-9eb5-22d32ec37402] Failed to start libvirt guest: libvirt.libvirtError:
> Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-
> qemu\x2d48\x2dinstance\x2d0000026b.scope/emulator/cpuset.cpus': Permission
> denied
> 2021-06-29 12:33:10.150 1310945 INFO os_vif [req-4f6fc6aa-04d6-4dc0-921f-
> 2913b40a76a9 2af528fdf3244e15b4f3f8fcfc0889c5 890eb2b7d1b8488aa88de7c34d08817a -
> default default] Successfully unplugged vif
> VIFOpenVSwitch(active=False,address=fa:16:3e:ba:3d:c8,bridge_name='br-
> int',has_traffic_filtering=True,id=a991cd33-2610-4823-a471-
> 62171037e1b5,network=Network(a0d85af2-a991-4102-8453-
> ba68c5e10b65),plugin='ovs',port_profile=VIFPortProfileOpenVSwitch,preserve_on_de
> lete=False,vif_name='tapa991cd33-26')
> 2021-06-29 12:33:10.151 1310945 INFO nova.virt.libvirt.driver [req-4f6fc6aa-
> 04d6-4dc0-921f-2913b40a76a9 2af528fdf3244e15b4f3f8fcfc0889c5
> 890eb2b7d1b8488aa88de7c34d08817a - default default] [instance: ed87bf68-b631-
> 4a00-9eb5-22d32ec37402] Deleting instance files
> /var/lib/nova/instances/ed87bf68-b631-4a00-9eb5-22d32ec37402_del
> 2021-06-29 12:33:10.152 1310945 INFO nova.virt.libvirt.driver [req-4f6fc6aa-
> 04d6-4dc0-921f-2913b40a76a9 2af528fdf3244e15b4f3f8fcfc0889c5
> 890eb2b7d1b8488aa88de7c34d08817a - default default] [instance: ed87bf68-b631-
> 4a00-9eb5-22d32ec37402] Deletion of /var/lib/nova/instances/ed87bf68-b631-4a00-
> 9eb5-22d32ec37402_del complete
> 2021-06-29 12:33:10.258 1310945 ERROR nova.compute.manager [req-4f6fc6aa-04d6-
> 4dc0-921f-2913b40a76a9 2af528fdf3244e15b4f3f8fcfc0889c5
> 890eb2b7d1b8488aa88de7c34d08817a - default default] [instance: ed87bf68-b631-
> 4a00-9eb5-22d32ec37402] Instance failed to spawn: libvirt.libvirtError: Unable
> to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-
> qemu\x2d48\x2dinstance\x2d0000026b.scope/emulator/cpuset.cpus': Permission
> denied
>
> Any advise how to fix this permission issue ?
>
> I have manually created the directory machine-qemu in
> /sys/fs/cgroup/cpuset/machine.slice/ but still having the same error.
>
> I have also tried to set [compute] cpu_shared_set AND [compute]
> cpu_dedicated_set  they are also giving the same error.

There are quite a few bugs about this [1][2]. It seems most of them are caused
by CPUs being offlined. Have you offline CPUs? Are the CPUs listed in the mask
all available?

Stephen

[1] https://bugzilla.redhat.com/show_bug.cgi?id=1609785
[2] https://bugzilla.redhat.com/show_bug.cgi?id=1842716

> Using ubuntu20.04 and qemu-kvm 4.2.
>
> Ammad
>
> On Fri, Jun 25, 2021 at 10:54 AM Sean Mooney <smooney@redhat.com> wrote:
> > On Fri, 2021-06-25 at 10:02 +0500, Ammad Syed wrote:
> > > Hi,
> > >
> > > I am using openstack wallaby on ubuntu 20.04 and kvm. I am working to make
> > > optimized flavor properties that should provide optimal performance. I was
> > > reviewing the document below.
> > >
> > > https://docs.openstack.org/nova/wallaby/admin/cpu-topologies.html
> > >
> > > I have two socket AMD compute node. The workload running on nodes are mixed
> > > workload.
> > >
> > > My question is should I use default nova CPU topology and NUMA node that
> > > nova deploys instance by default OR should I use hw:cpu_sockets='2'
> > > and hw:numa_nodes='2'.
> > the latter hw:cpu_sockets='2' and hw:numa_nodes='2' should give you better
> > performce
> > however you should also set hw:mem_page_size=small or hw:mem_page_size=any
> > when you enable virtual numa policies we afinities the guest memory to host
> > numa nodes.
> > This can lead to Out of memory evnet on the the host numa nodes which can
> > result in vms
> > being killed by the host kernel memeory reaper if you do not enable numa aware
> > memeory
> > trackign iin nova which is done by setting hw:mem_page_size. setting 
> > hw:mem_page_size has
> > the side effect of of disabling memory over commit so you have to bare that in
> > mind.
> > if you are using numa toplogy you should almost always also use hugepages
> > which are enabled
> > using  hw:mem_page_size=large this however requires you to configure
> > hupgepages in the host
> > at boot.
> > >
> > > Which one from above provide best instance performance ? or any other
> > > tuning should I do ?
> >
> > in the libvirt driver the default cpu toplogy we will genergated
> > is 1 thread per core, 1 core per socket and 1 socket per flavor.vcpu.
> > (technially this is an undocumeted implemation detail that you should not rely
> > on, we have the hw:cpu_* element if you care about the toplogy)
> >
> > this was more effincet in the early days of qemu/openstack but has may issue
> > when software is chagne per sokcet or oepreating systems have
> > a limit on socket supported such as windows.
> >
> > generally i advies that you set hw:cpu_sockets to the typical number of
> > sockets on the underlying host.
> > simialrly if the flavor will only be run on host with SMT/hypertreading
> > enabled on you shoudl set hw:cpu_threads=2
> >
> > the flavor.vcpus must be devisable by the product of hw:cpu_sockets,
> > hw:cpu_cores and hw:cpu_threads if they are set.
> >
> > so if you have  hw:cpu_threads=2 it must be devisable by 2
> > if you have  hw:cpu_threads=2 and hw:cpu_sockets=2 flavor.vcpus must be a
> > multiple of 4
> > >
> > > The note in the URL (CPU topology sesion) suggests that I should stay with
> > > default options that nova provides.
> > in generaly no you should aling it to the host toplogy if you have similar
> > toplogy across your data center.
> > the default should always just work but its not nessisarly optimal and window
> > sguest might not boot if you have too many sockets.
> > windows 10 for exmple only supprot 2 socket so you could only have 2
> > flavor.vcpus if you used the default toplogy.
> >
> > >
> > > Currently it also works with libvirt/QEMU driver but we don’t recommend it
> > > in production use cases. This is because vCPUs are actually running in one
> > > thread on host in qemu TCG (Tiny Code Generator), which is the backend for
> > > libvirt/QEMU driver. Work to enable full multi-threading support for TCG
> > > (a.k.a. MTTCG) is on going in QEMU community. Please see this MTTCG project
> > > <http://wiki.qemu.org/Features/tcg-multithread> page for detail.
> > we do not gnerally recommende using qemu without kvm in produciton.
> > the mttcg backend is useful in cases where you want to emulate other plathform
> > but that usecsae
> > is not currently supported in nova.
> > for your deployment you should use libvirt with kvm and you should also
> > consider if you want to support
> > nested virtualisation or not.
> > >
> > >
> > > Ammad
> >
> >
>
>




--
Regards,


Syed Ammad Ali


--
Regards,


Syed Ammad Ali