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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.
This problem is also existing for iothreadpin of cputune. And It's also existed in RHEL6, I will clone it to RHEL6.
Patch proposed upstream: https://www.redhat.com/archives/libvir-list/2015-January/msg00845.html
I've just pushed the patch upstream: commit bbd3eb50987676f486effe55feec1fe0d01cafd0 Author: Michal Privoznik <mprivozn@redhat.com> AuthorDate: Thu Jan 22 13:57:22 2015 +0100 Commit: Michal Privoznik <mprivozn@redhat.com> 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@redhat.com> v1.2.12-50-gbbd3eb5
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
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