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Osier Yang
a39f69d2bb
qemu: Set cpuset.cpus for domain process
When either "cpuset" of <vcpu> is specified, or the "placement" of <vcpu> is "auto", only setting the cpuset.mems might cause the guest starting to fail. E.g. ("placement" of both <vcpu> and <numatune> is "auto"): 1) Related XMLs <vcpu placement='auto'>4</vcpu> <numatune> <memory mode='strict' placement='auto'/> </numatune> 2) Host NUMA topology % numactl --hardware available: 8 nodes (0-7) node 0 cpus: 0 4 8 12 16 20 24 28 node 0 size: 16374 MB node 0 free: 11899 MB node 1 cpus: 32 36 40 44 48 52 56 60 node 1 size: 16384 MB node 1 free: 15318 MB node 2 cpus: 2 6 10 14 18 22 26 30 node 2 size: 16384 MB node 2 free: 15766 MB node 3 cpus: 34 38 42 46 50 54 58 62 node 3 size: 16384 MB node 3 free: 15347 MB node 4 cpus: 3 7 11 15 19 23 27 31 node 4 size: 16384 MB node 4 free: 15041 MB node 5 cpus: 35 39 43 47 51 55 59 63 node 5 size: 16384 MB node 5 free: 15202 MB node 6 cpus: 1 5 9 13 17 21 25 29 node 6 size: 16384 MB node 6 free: 15197 MB node 7 cpus: 33 37 41 45 49 53 57 61 node 7 size: 16368 MB node 7 free: 15669 MB 4) cpuset.cpus will be set as: (from debug log) 2013-05-09 16:50:17.296+0000: 417: debug : virCgroupSetValueStr:331 : Set value '/sys/fs/cgroup/cpuset/libvirt/qemu/toy/cpuset.cpus' to '0-63' 5) The advisory nodeset got from querying numad (from debug log) 2013-05-09 16:50:17.295+0000: 417: debug : qemuProcessStart:3614 : Nodeset returned from numad: 1 6) cpuset.mems will be set as: (from debug log) 2013-05-09 16:50:17.296+0000: 417: debug : virCgroupSetValueStr:331 : Set value '/sys/fs/cgroup/cpuset/libvirt/qemu/toy/cpuset.mems' to '0-7' I.E, the domain process's memory is restricted on the first NUMA node, however, it can use all of the CPUs, which will likely cause the domain process to fail to start because of the kernel fails to allocate memory with the the memory policy as "strict". % tail -n 20 /var/log/libvirt/qemu/toy.log ... 2013-05-09 05:53:32.972+0000: 7318: debug : virCommandHandshakeChild:377 : Handshake with parent is done char device redirected to /dev/pts/2 (label charserial0) kvm_init_vcpu failed: Cannot allocate memory ... Signed-off-by: Peter Krempa <pkrempa@redhat.com>
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LibVirt : simple API for virtualization Libvirt is a C toolkit to interact with the virtualization capabilities of recent versions of Linux (and other OSes). It is free software available under the GNU Lesser General Public License. Virtualization of the Linux Operating System means the ability to run multiple instances of Operating Systems concurrently on a single hardware system where the basic resources are driven by a Linux instance. The library aim at providing long term stable C API initially for the Xen paravirtualization but should be able to integrate other virtualization mechanisms if needed. Daniel Veillard <veillard@redhat.com>
Description
Libvirt provides a portable, long term stable C API for managing the
virtualization technologies provided by many operating systems. It
includes support for QEMU, KVM, Xen, LXC, bhyve, Virtuozzo, VMware
vCenter and ESX, VMware Desktop, Hyper-V, VirtualBox and the POWER
Hypervisor.
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