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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 at 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
> > 
> > 
> 
>