创建一个多VCPU的虚拟机，flavor如下
+----+-----------+-----------+------+-----------+------+-------+-------------+-----------+ | ID | Name | Memory_MB | Disk | Ephemeral | Swap | VCPUs | RXTX_Factor | Is_Public | +----+-----------+-----------+------+-----------+------+-------+-------------+-----------+ | 3 | m1.medium | 4096 | 40 | 0 | | 2 | 1.0 | True |
VCPU调度情况
virsh # list Id Name State ---------------------------------------------------- 8 instance-00000007 running virsh # virsh # vcpuinfo 8 VCPU: 0 CPU: 3 State: running CPU time: 21.6s CPU Affinity: yyyy VCPU: 1 CPU: 3 State: running CPU time: 42.9s CPU Affinity: yyyy
再运行一次
virsh # vcpuinfo 8 VCPU: 0 CPU: 3 State: running CPU time: 21.8s CPU Affinity: yyyy VCPU: 1 CPU: 2 State: running CPU time: 48.1s CPU Affinity: yyyy
可见VCPU0~1对应着物理CPU0~3随意调度
下面想要强行将VCPU和CPU的对应关系绑定
首先一种方法，想到的是通过Linux的taskset命令，直接将qemu进程给设置affinity
查看进程号
lihui@devstack:~$ ps aux | grep qemu-system-x86_64 lihui 3088 0.0 0.0 15720 920 pts/1 S+ 00:23 0:00 grep --color=auto qemu-system-x86_64 libvirt+ 11196 9.0 2.4 7821508 400204 ? Sl 00:02 1:53 /usr/bin/qemu-system-x86_64 -name instance-00000007
绑定
lihui@devstack:~$ sudo taskset -cp 3 11196 pid 11196's current affinity list: 0-3 pid 11196's new affinity list: 3
验证，多运行几次，永不会变，不信用top再观察一下，进程确实是稳定在CPU3上
lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 3 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 3 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 3 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 3
这时候看一下virsh的对应关系，出现了神奇的一幕
virsh # vcpuinfo 8 VCPU: 0 CPU: 3 State: running CPU time: 24.0s CPU Affinity: yyyy VCPU: 1 CPU: 3 State: running CPU time: 118.9s CPU Affinity: ---y virsh # vcpuinfo 8 VCPU: 0 CPU: 1 State: running CPU time: 24.0s CPU Affinity: yyyy VCPU: 1 CPU: 3 State: running CPU time: 119.0s CPU Affinity: ---y
从最后一项CPU Affinity可以看出来，VCPU1确实被绑定了和CPU3对应，但是VCPU0却依旧在0~3上随机调度
而且就算通过taskset多绑几次，得到的结果都一样，VCPU0依旧在CPU0~3上调度
这种结果的原因未知，可能跟taskset原理只负责绑定进程到指定CPU，还有虚拟机VCPU原理有关
下面再通过virsh强制绑定
virsh # vcpupin 8 0 2 virsh # vcpupin 8 1 1
将VCPU0绑定CPU2，VCPU1绑定CPU1，看下结果
virsh # vcpuinfo 8 VCPU: 0 CPU: 2 State: running CPU time: 26.1s CPU Affinity: --y- VCPU: 1 CPU: 1 State: running CPU time: 185.1s CPU Affinity: -y--
显然这是对的，因为CPU Affinity已经固定死了
查看此时进程
lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 1 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 1 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 1 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 1 lihui@devstack:~$ ps -eo pid,psr | grep 11196 11196 1
同时在虚拟机的xml配置文件中能看到对应信息
vcpupin vcpu='0' cpuset='2' vcpupin vcpu='1' cpuset='1'
既然如此，重启一下虚拟机看看
nova reboot --hard e77bb302-15b3-4e91-836c-3bdd78c8044a
最终查看一下VCPU的绑定情况
virsh # list Id Name State ---------------------------------------------------- 9 instance-00000007 running virsh # vcpuinfo 9 VCPU: 0 CPU: 0 State: running CPU time: 18.1s CPU Affinity: yyyy VCPU: 1 CPU: 1 State: running CPU time: 7.4s CPU Affinity: yyyy
首先Id变了，然后CPU Affinity又恢复到初始状态了，跟想象中不太一样哇，通过dumpxml得到虚拟机的配置信息，果然上面cpuset信息都没了
看来想知道这些绑定的流程，需要了解下原理，通过什么实现的才行
