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Description of problem: Currently cpu pinning information can be configured only for active VCPUs. On cpu hotplug the cpu has to be pinned explicitly. On vCPU hot-unplug the information is deleted. Libvirt should be able to keep the information for vCPUs that are configured as inactive and reuse them afterwards. Note: we do it with scheduler type and priority currently
This feature was added upstream by: commit 02ae21deb3b5d91a6bd91d773265b6622a102985 Author: Peter Krempa <pkrempa> Date: Fri Feb 12 14:57:45 2016 +0100 qemu: add support for offline vcpupin Allow pinning for inactive vcpus. The pinning mask will be automatically applied as we would apply the default mask in case of a cpu hotplug. Setting the scheduler settings for a vcpu has the same semantics. .. and a lot of refactors necessary for that change. v1.3.2-96-g02ae21d
This bug was accidentally moved from POST to MODIFIED via an error in automation, please see mmccune with any questions
Verify this bug with libvirt-2.0.0-5.el7.x86_64: 1. prepare a inactive guest: # virsh dumpxml r7 ... <vcpu placement='static' current='1'>10</vcpu> ... 2. check vcpupin: # virsh vcpupin r7 --config VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 0-23 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 0-23 9: 0-23 3. bind vcpu to cpu # virsh vcpupin r7 2 1-3 --config # virsh vcpupin r7 9 23 --config 4. check inactive xml: # virsh dumpxml r7 ... <vcpu placement='static' current='1'>10</vcpu> <cputune> <vcpupin vcpu='2' cpuset='1-3'/> <vcpupin vcpu='9' cpuset='23'/> </cputune> ... # virsh vcpupin r7 VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 1-3 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 0-23 9: 23 5. start guest and recheck guest xml and vcpupin: # virsh start r7 Domain r7 started # virsh vcpupin r7 VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 1-3 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 0-23 9: 23 # virsh dumpxml r7 ... <vcpu placement='static' current='1'>10</vcpu> <cputune> <vcpupin vcpu='2' cpuset='1-3'/> <vcpupin vcpu='9' cpuset='23'/> </cputune> ... 6. hotplug vcpu 2: # virsh setvcpus r7 3 7. check vcpupin,taskset and cgroup: # virsh vcpupin r7 VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 1-3 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 0-23 9: 23 # cat /proc/`pidof qemu-kvm`/task/*/status Name: CPU 2/KVM ... Cpus_allowed: 00000e Cpus_allowed_list: 1-3 ... # cgget -g cpuset /machine.slice/machine-qemu\\x2d2\\x2dr7.scope/vcpu2 /machine.slice/machine-qemu\x2d2\x2dr7.scope/vcpu2: 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: 0-3 cpuset.cpus: 1-3 8. change vcpu 8 vcpupin on live: # virsh vcpupin r7 8 1 # virsh vcpupin r7 VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 1-3 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 1 9: 23 9. hot-plug vpu 8: # virsh setvcpus r7 9 # virsh vcpupin r7 VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 1-3 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 1 9: 23 10. check taskset and cgroup: # taskset -c -p 23596 pid 23596's current affinity list: 1 # cgget -g cpuset /machine.slice/machine-qemu\\x2d2\\x2dr7.scope/vcpu8 /machine.slice/machine-qemu\x2d2\x2dr7.scope/vcpu8: 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: 0-3 cpuset.cpus: 1 11. restart libvirtd and recheck: # service libvirtd restart Redirecting to /bin/systemctl restart libvirtd.service # virsh vcpupin r7 VCPU: CPU Affinity ---------------------------------- 0: 0-23 1: 0-23 2: 1-3 3: 0-23 4: 0-23 5: 0-23 6: 0-23 7: 0-23 8: 1 9: 23 # virsh dumpxml r7 ... <vcpu placement='static' current='9'>10</vcpu> <cputune> <vcpupin vcpu='2' cpuset='1-3'/> <vcpupin vcpu='8' cpuset='1'/> <vcpupin vcpu='9' cpuset='23'/> </cputune> ...
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/RHSA-2016-2577.html