VCPU的调度信息

作者: LiHui 分类: OpenStack,Virtualization 发布时间: 2015-11-03 00:10

一直没有弄明白宿主机CPU和虚拟机VCPU的对应关系是如何调度,或者说如何辨别,刚刚突然发现virsh可以直接查到这项信息

首先在一个安装有devstack的物理机上操作,当然假如有分布式openstack的节点机环境操作也行

# virsh
Welcome to virsh, the virtualization interactive terminal.

Type:  'help' for help with commands
       'quit' to quit

virsh # list
 Id    Name                           State
----------------------------------------------------
 2     instance-00000001              running

这里有一项Id,要认清楚,它是与虚拟机实例一一对应的关系,没有其它的含义,但是下面会用到

查看虚拟机VCPU和物理CPU的对应关系

virsh # vcpuinfo 2
VCPU:           0
CPU:            1
State:          running
CPU time:       3279.4s
CPU Affinity:   yy

可以得到VCPU0被调度到宿主机CPU1上,目前是运行状态,运行的时间为3279.4秒,而CPU的亲和性信息显示该虚拟机实例能在物理CPU0和CPU1上调度,而且看上去宿主机就只有两个核

查一下

~$ lscpu
Architecture:          x86_64
CPU op-mode(s):        32-bit, 64-bit
Byte Order:            Little Endian
CPU(s):                2
On-line CPU(s) list:   0,1
Thread(s) per core:    1
Core(s) per socket:    1
Socket(s):             2
NUMA node(s):          1
Vendor ID:             GenuineIntel
CPU family:            6
Model:                 42
Stepping:              1
CPU MHz:               2599.998
BogoMIPS:              5199.99
Hypervisor vendor:     KVM
Virtualization type:   full
L1d cache:             32K
L1i cache:             32K
L2 cache:              4096K
NUMA node0 CPU(s):     0,1

的确只有两个逻辑核,而且还发现了其实这台宿主机也是一台KVM的虚拟机而已

还可以继续查看某虚拟机可以使用哪些物理CPU

virsh # emulatorpin 2
emulator: CPU Affinity
----------------------------------
       *: 0-1

如此一来,说明0和1都可用,也就是说该虚拟机VCPU可以调度到任何物理CPU上

既然如此,查一下虚拟机进程所在的物理CPU

~$ ps aux | grep qemu-system-x86_64
lihui     6564  0.0  0.0  15720   920 pts/1    S+   00:12   0:00 grep --color=auto qemu-system-x86_64
libvirt+  8974  9.6  4.0 1652212 249448 ?      Sl   Oct25 1240:25 /usr/bin/qemu-system-x86_64 -name instance-00000001 -S -machine pc-i440fx-trusty,accel=tcg,usb=off -m 512 -realtime mlock=off -smp 1,sockets=1,cores=1,threads=1 -uuid ecdd5b09-39f9-4bfa-953a-4bce8e76424e -smbios type=1,manufacturer=OpenStack Foundation,product=OpenStack Nova,version=2013.2.3,serial=3237b2cc-c28f-49cb-a3c6-3f993ce98dc3,uuid=ecdd5b09-39f9-4bfa-953a-4bce8e76424e -no-user-config -nodefaults -chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/instance-00000001.monitor,server,nowait -mon chardev=charmonitor,id=monitor,mode=control -rtc base=utc -no-shutdown -boot strict=on -device piix3-usb-uhci,id=usb,bus=pci.0,addr=0x1.0x2 -drive file=/opt/stack/data/nova/instances/ecdd5b09-39f9-4bfa-953a-4bce8e76424e/disk,if=none,id=drive-virtio-disk0,format=qcow2,cache=none -device virtio-blk-pci,scsi=off,bus=pci.0,addr=0x4,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1 -netdev tap,fd=24,id=hostnet0 -device virtio-net-pci,netdev=hostnet0,id=net0,mac=fa:16:3e:4f:60:ed,bus=pci.0,addr=0x3 -chardev file,id=charserial0,path=/opt/stack/data/nova/instances/ecdd5b09-39f9-4bfa-953a-4bce8e76424e/console.log -device isa-serial,chardev=charserial0,id=serial0 -chardev pty,id=charserial1 -device isa-serial,chardev=charserial1,id=serial1 -device usb-tablet,id=input0 -vnc 127.0.0.1:0 -k en-us -device cirrus-vga,id=video0,bus=pci.0,addr=0x2 -device virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x5

最后通过ps命令查询

~$ ps -eo pid,psr | grep 8974
 8974   0

看到这个结果就比较奇怪了,按理说,假如说整个虚拟机所在进程是运行在物理CPU0上,那么它的VCPU会被调度到CPU1上么?难道不会继承么,抱着怀疑的态度,通过top查看一下cpu affinity

Tasks: 210 total,   2 running, 208 sleeping,   0 stopped,   0 zombie
%Cpu0  : 34.6 us, 35.2 sy,  0.0 ni, 30.2 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  : 25.0 us, 20.0 sy,  0.0 ni, 54.7 id,  0.0 wa,  0.3 hi,  0.0 si,  0.0 st
KiB Mem:   6112692 total,  5222884 used,   889808 free,   219592 buffers
KiB Swap:        0 total,        0 used,        0 free.  2280096 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                             P
22023 lihui     20   0  227636  58996   4940 S  12.6  1.0   4041:10 python                                                                              1
 8974 libvirt+  20   0 1652212 249448   9832 S   6.3  4.1   1241:26 qemu-system-x86                                                                     1

猛然发现,qemu进程不停在0和1之间跳动

Tasks: 213 total,   4 running, 209 sleeping,   0 stopped,   0 zombie
%Cpu0  : 33.1 us, 29.5 sy,  0.0 ni, 36.4 id,  1.0 wa,  0.0 hi,  0.0 si,  0.0 st
%Cpu1  : 33.8 us, 26.8 sy,  0.0 ni, 39.5 id,  0.0 wa,  0.0 hi,  0.0 si,  0.0 st
KiB Mem:   6112692 total,  5229108 used,   883584 free,   219592 buffers
KiB Swap:        0 total,        0 used,        0 free.  2280976 cached Mem

  PID USER      PR  NI    VIRT    RES    SHR S  %CPU %MEM     TIME+ COMMAND                                                                             P
22023 lihui     20   0  227636  58996   4940 S  10.3  1.0   4041:25 python                                                                              0
 8974 libvirt+  20   0 1652212 249448   9832 S   9.3  4.1   1241:43 qemu-system-x86                                                                     0
23177 lihui     20   0  265732  79680   5800 R   5.6  1.3 228:02.12 nova-conductor                                                                      0

原来如此,多执行几遍ps查询命令,也能够得到同样的结果

lihui@devstack:~$ ps -eo pid,psr | grep 8974
 8974   0
lihui@devstack:~$ ps -eo pid,psr | grep 8974
 8974   0
lihui@devstack:~$ ps -eo pid,psr | grep 8974
 8974   1
lihui@devstack:~$ ps -eo pid,psr | grep 8974
 8974   1
lihui@devstack:~$ ps -eo pid,psr | grep 8974
 8974   0

 

 这里由于虚拟机只分配了1个vcpu,因此只能看到一个调度信息,假如是多核实例,应该可以列出所有vcpu的调度信息

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