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Description of problem: """ If attribute emulatorpin of cputune is specified, cpuset specified by vcpu here will be ignored; Similarly, For virtual CPUs which has vcpupin specified, cpuset specified by cpuset here will be ignored; For virtual CPUs which doesn't have vcpupin specified, it will be pinned to the physical CPUs specified by cpuset here """ Version-Release number of selected component (if applicable): libvirt-1.2.7-1.el7.x86_64 How reproducible: 100% Steps to Reproduce: 1. Set 'cpuset' in <vcpu> element: # virsh dumpxml test|grep cpu <vcpu placement='static' cpuset='1'>1</vcpu> # virsh start test 2. Do vcpupin or emulatorpin # virsh vcpupin test 0 0 error: Requested operation is not valid: failed to set cpuset.cpus in cgroup for vcpu 0 # virsh emulatorpin test 0 error: Requested operation is not valid: failed to set cpuset.cpus in cgroup for emulator threads or set 'cpuset' in <vcpu> element and set 'cpuset' in <cputune> element, then try to start domain # virsh dumpxml test|grep cpu <vcpu placement='static' cpuset='1'>1</vcpu> <cputune> <vcpupin vcpu='0' cpuset='0'/> </cputune> # virsh start test error: Failed to start domain test error: Unable to write to '/sys/fs/cgroup/cpuset/machine.slice/machine-qemu\x2dtest.scope/vcpu0/cpuset.cpus': Permission denied Actual results: Expected results: 'cpuset' specified by vcpu should be ignored if attribute 'emulatorpin' or 'vcpupin' is specified Additional info: Come from bug https://bugzilla.redhat.com/show_bug.cgi?id=838070#c17
Fixed upstream: commit f0fa9080d47b7aedad6f4884b8879d88688752a6 Author: Peter Krempa <pkrempa@redhat.com> Date: Fri Mar 27 10:23:19 2015 +0100 qemu: cgroup: Properly set up vcpu pinning When the default cpuset or automatic numa placement is used libvirt would place the whole parent cgroup in the specified cpuset. This then disallowed to re-pin the vcpus to a different cpu. This patch pins only the vcpu threads to the default cpuset and thus allows to re-pin them later. The following config would fail to start: <domain type='kvm'> ... <vcpu placement='static' cpuset='0-1' current='2'>4</vcpu> <cputune> <vcpupin vcpu='0' cpuset='2-3'/> ... This is a regression since a39f69d2b. v1.2.14-4-gf0fa908
Verify this bug with libvirt-1.2.17-2.el7.x86_64: 1. prepare a guest with cpuset and vcpupin, iothreadpin, emulatorpin: # virsh dumpxml test4 <vcpu placement='static' cpuset='2' current='2'>4</vcpu> <iothreads>3</iothreads> <cputune> <vcpupin vcpu='0' cpuset='1'/> <emulatorpin cpuset='3'/> <iothreadpin iothread='1' cpuset='0'/> </cputune> 2. start it: # virsh start test4 Domain test4 started 3. check cgroup # cgget -g cpuset /machine.slice/machine-qemu\\x2dtest4.scope/emulator /machine.slice/machine-qemu\x2dtest4.scope/emulator: 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/iothread1 /machine.slice/machine-qemu\x2dtest4.scope/iothread1: 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: 0 # cgget -g cpuset /machine.slice/machine-qemu\\x2dtest4.scope/vcpu0 /machine.slice/machine-qemu\x2dtest4.scope/vcpu0: 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 4. check other # cgget -g cpuset /machine.slice/machine-qemu\\x2dtest4.scope/vcpu1 /machine.slice/machine-qemu\x2dtest4.scope/vcpu1: 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/iothread2 /machine.slice/machine-qemu\x2dtest4.scope/iothread2: 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/iothread3 /machine.slice/machine-qemu\x2dtest4.scope/iothread3: 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
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