红帽全球峰会13.3.2. Emulatorpin 的工作原理
默认情况下，Red Hat OpenStack Platform 部署使用以下设置：
virsh dumpxml instance-0000001d
(...)
<vcpu placement='static'>4</vcpu>
<cputune>
<shares>4096</shares>
<vcpupin vcpu='0' cpuset='34'/>
<vcpupin vcpu='1' cpuset='14'/>
<vcpupin vcpu='2' cpuset='10'/>
<vcpupin vcpu='3' cpuset='30'/>
<emulatorpin cpuset='10,14,30,34'/>
</cputune>
(...)
virsh dumpxml instance-0000001d
(...)
<vcpu placement='static'>4</vcpu>
<cputune>
<shares>4096</shares>
<vcpupin vcpu='0' cpuset='34'/>
<vcpupin vcpu='1' cpuset='14'/>
<vcpupin vcpu='2' cpuset='10'/>
<vcpupin vcpu='3' cpuset='30'/>
<emulatorpin cpuset='10,14,30,34'/>
</cputune>
(...)这会导致仿真程序线程的无法预计分配，如 qemu-kvm、vnc_worker 等：
ps -T -p 73517 taskset -apc 73517
[root@overcloud-compute-0 ~]# ps -T -p 73517
PID SPID TTY TIME CMD
73517 73517 ? 00:00:00 qemu-kvm
73517 73527 ? 00:00:00 qemu-kvm
73517 73535 ? 00:00:06 CPU 0/KVM
73517 73536 ? 00:00:02 CPU 1/KVM
73517 73537 ? 00:00:03 CPU 2/KVM
73517 73538 ? 00:00:02 CPU 3/KVM
73517 73540 ? 00:00:00 vnc_worker
[root@overcloud-compute-0 ~]# taskset -apc 73517
pid 73517's current affinity list: 10,14,30,34
pid 73527's current affinity list: 10,14,30,34
pid 73535's current affinity list: 34
pid 73536's current affinity list: 14
pid 73537's current affinity list: 10
pid 73538's current affinity list: 30
pid 73540's current affinity list: 10,14,30,34virsh vcpupin instance-0000001d | awk '$NF~/[0-9]+/ {print $NF}' | sort -n | while read CPU; do sed '/cpu#/,/runnable task/{//!d}' /proc/sched_debug | sed -n "/^cpu#${CPU},/,/^$/p" ; done
[root@overcloud-compute-0 ~]# virsh vcpupin instance-0000001d | awk '$NF~/[0-9]+/ {print $NF}' | sort -n | while read CPU; do sed '/cpu#/,/runnable task/{//!d}' /proc/sched_debug | sed -n "/^cpu#${CPU},/,/^$/p" ; done
cpu#10, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/10 64 0.000000 107 0 0.000000 90.232791 0.000000 0 /
ksoftirqd/10 65 -13.045337 3 120 0.000000 0.004679 0.000000 0 /
kworker/10:0 66 -12.892617 40 120 0.000000 0.157359 0.000000 0 /
kworker/10:0H 67 -9.320550 8 100 0.000000 0.015065 0.000000 0 /
kworker/10:1 17996 9695.675528 23 120 0.000000 0.222805 0.000000 0 /
qemu-kvm 73517 1994.534332 27105 120 0.000000 886.203254 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
qemu-kvm 73527 722.347466 84 120 0.000000 18.236155 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
CPU 2/KVM 73537 3356.749162 18051 120 0.000000 3370.045619 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu2
vnc_worker 73540 354.007735 1 120 0.000000 0.047002 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 74584 1970.499537 5 120 0.000000 0.130143 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 74585 1970.492700 4 120 0.000000 0.071887 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 74586 1982.467246 3 120 0.000000 0.033604 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 74587 1994.520768 1 120 0.000000 0.076039 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 74588 2006.500153 1 120 0.000000 0.004878 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
cpu#14, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/14 88 0.000000 107 0 0.000000 90.107596 0.000000 0 /
ksoftirqd/14 89 -13.045376 3 120 0.000000 0.004782 0.000000 0 /
kworker/14:0 90 -12.921990 40 120 0.000000 0.128166 0.000000 0 /
kworker/14:0H 91 -9.321186 8 100 0.000000 0.016870 0.000000 0 /
kworker/14:1 17999 6247.571171 5 120 0.000000 0.028576 0.000000 0 /
CPU 1/KVM 73536 2274.381281 6679 120 0.000000 2287.691654 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu1
cpu#30, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/30 180 0.000000 107 0 0.000000 89.206960 0.000000 0 /
ksoftirqd/30 181 -13.045892 3 120 0.000000 0.003828 0.000000 0 /
kworker/30:0 182 -12.929272 40 120 0.000000 0.120754 0.000000 0 /
kworker/30:0H 183 -9.321056 8 100 0.000000 0.018042 0.000000 0 /
kworker/30:1 18012 6234.935501 5 120 0.000000 0.026505 0.000000 0 /
CPU 3/KVM 73538 2474.183301 12595 120 0.000000 2487.479666 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu3
cpu#34, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/34 204 0.000000 107 0 0.000000 89.067908 0.000000 0 /
ksoftirqd/34 205 -13.046824 3 120 0.000000 0.002884 0.000000 0 /
kworker/34:0 206 -12.922407 40 120 0.000000 0.127423 0.000000 0 /
kworker/34:0H 207 -9.320822 8 100 0.000000 0.017381 0.000000 0 /
kworker/34:1 18016 10788.797590 7 120 0.000000 0.042631 0.000000 0 /
CPU 0/KVM 73535 5969.227225 14233 120 0.000000 5983.425363 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu0可使用 virsh 模拟器线程移动模拟程序线程：
virsh emulatorpin instance-0000001d 34
virsh emulatorpin instance-0000001d 34请注意，所有非 CPU 线程更改的关联性。
ps -T -p 73517 taskset -apc 73517
[root@overcloud-compute-0 ~]# ps -T -p 73517
PID SPID TTY TIME CMD
73517 73517 ? 00:00:00 qemu-kvm
73517 73527 ? 00:00:00 qemu-kvm
73517 73535 ? 00:00:06 CPU 0/KVM
73517 73536 ? 00:00:02 CPU 1/KVM
73517 73537 ? 00:00:03 CPU 2/KVM
73517 73538 ? 00:00:02 CPU 3/KVM
73517 73540 ? 00:00:00 vnc_worker
[root@overcloud-compute-0 ~]# taskset -apc 73517
pid 73517's current affinity list: 34
pid 73527's current affinity list: 34
pid 73535's current affinity list: 34
pid 73536's current affinity list: 14
pid 73537's current affinity list: 10
pid 73538's current affinity list: 30
pid 73540's current affinity list: 34
请注意在 /proc/sched_debug 中历史数据中的切换数。在以下示例中，PID 73517 已移至 cpu#34。其他仿真程序 worker 没有从最后的输出运行，因此仍然会在 cpu#10 上显示：
virsh vcpupin instance-0000001d | awk '$NF~/[0-9]+/ {print $NF}' | sort -n | while read CPU; do sed '/cpu#/,/runnable task/{//!d}' /proc/sched_debug | sed -n "/^cpu#${CPU},/,/^$/p" ; done
[root@overcloud-compute-0 ~]# virsh vcpupin instance-0000001d | awk '$NF~/[0-9]+/ {print $NF}' | sort -n | while read CPU; do sed '/cpu#/,/runnable task/{//!d}' /proc/sched_debug | sed -n "/^cpu#${CPU},/,/^$/p" ; done
cpu#10, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/10 64 0.000000 107 0 0.000000 90.232791 0.000000 0 /
ksoftirqd/10 65 -13.045337 3 120 0.000000 0.004679 0.000000 0 /
kworker/10:0 66 -12.892617 40 120 0.000000 0.157359 0.000000 0 /
kworker/10:0H 67 -9.320550 8 100 0.000000 0.015065 0.000000 0 /
kworker/10:1 17996 9747.429082 26 120 0.000000 0.255547 0.000000 0 /
qemu-kvm 73527 722.347466 84 120 0.000000 18.236155 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
CPU 2/KVM 73537 3424.520709 21610 120 0.000000 3437.817166 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu2
vnc_worker 73540 354.007735 1 120 0.000000 0.047002 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
cpu#14, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/14 88 0.000000 107 0 0.000000 90.107596 0.000000 0 /
ksoftirqd/14 89 -13.045376 3 120 0.000000 0.004782 0.000000 0 /
kworker/14:0 90 -12.921990 40 120 0.000000 0.128166 0.000000 0 /
kworker/14:0H 91 -9.321186 8 100 0.000000 0.016870 0.000000 0 /
kworker/14:1 17999 6247.571171 5 120 0.000000 0.028576 0.000000 0 /
CPU 1/KVM 73536 2283.094453 7028 120 0.000000 2296.404826 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu1
cpu#30, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/30 180 0.000000 107 0 0.000000 89.206960 0.000000 0 /
ksoftirqd/30 181 -13.045892 3 120 0.000000 0.003828 0.000000 0 /
kworker/30:0 182 -12.929272 40 120 0.000000 0.120754 0.000000 0 /
kworker/30:0H 183 -9.321056 8 100 0.000000 0.018042 0.000000 0 /
kworker/30:1 18012 6234.935501 5 120 0.000000 0.026505 0.000000 0 /
CPU 3/KVM 73538 2521.828931 14047 120 0.000000 2535.125296 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu3
cpu#34, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/34 204 0.000000 107 0 0.000000 89.067908 0.000000 0 /
ksoftirqd/34 205 -13.046824 3 120 0.000000 0.002884 0.000000 0 /
kworker/34:0 206 -12.922407 40 120 0.000000 0.127423 0.000000 0 /
kworker/34:0H 207 -9.320822 8 100 0.000000 0.017381 0.000000 0 /
kworker/34:1 18016 10788.797590 7 120 0.000000 0.042631 0.000000 0 /
qemu-kvm 73517 2.613794 27706 120 0.000000 941.839262 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
CPU 0/KVM 73535 5994.533905 15169 120 0.000000 6008.732043 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu0请注意，线程 73517 移到 cpu#34。现在，如果您与 VNC 会话交互，您可以看到 /proc/sched_debug 显示了 cpu#34 上的 vnc_worker 线程。
virsh vcpupin instance-0000001d | awk '$NF~/[0-9]+/ {print $NF}' | sort -n | while read CPU; do sed '/cpu#/,/runnable task/{//!d}' /proc/sched_debug | sed -n "/^cpu#${CPU},/,/^$/p" ; done
[root@overcloud-compute-0 ~]# virsh vcpupin instance-0000001d | awk '$NF~/[0-9]+/ {print $NF}' | sort -n | while read CPU; do sed '/cpu#/,/runnable task/{//!d}' /proc/sched_debug | sed -n "/^cpu#${CPU},/,/^$/p" ; done
cpu#10, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/10 64 0.000000 107 0 0.000000 90.232791 0.000000 0 /
ksoftirqd/10 65 -13.045337 3 120 0.000000 0.004679 0.000000 0 /
kworker/10:0 66 -12.892617 40 120 0.000000 0.157359 0.000000 0 /
kworker/10:0H 67 -9.320550 8 100 0.000000 0.015065 0.000000 0 /
kworker/10:1 17996 9963.300958 27 120 0.000000 0.273007 0.000000 0 /
qemu-kvm 73527 722.347466 84 120 0.000000 18.236155 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
CPU 2/KVM 73537 3563.793234 26162 120 0.000000 3577.089691 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu2
cpu#14, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/14 88 0.000000 107 0 0.000000 90.107596 0.000000 0 /
ksoftirqd/14 89 -13.045376 3 120 0.000000 0.004782 0.000000 0 /
kworker/14:0 90 -12.921990 40 120 0.000000 0.128166 0.000000 0 /
kworker/14:0H 91 -9.321186 8 100 0.000000 0.016870 0.000000 0 /
kworker/14:1 17999 6247.571171 5 120 0.000000 0.028576 0.000000 0 /
CPU 1/KVM 73536 2367.789075 9648 120 0.000000 2381.099448 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu1
cpu#30, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/30 180 0.000000 107 0 0.000000 89.206960 0.000000 0 /
ksoftirqd/30 181 -13.045892 3 120 0.000000 0.003828 0.000000 0 /
kworker/30:0 182 -12.929272 40 120 0.000000 0.120754 0.000000 0 /
kworker/30:0H 183 -9.321056 8 100 0.000000 0.018042 0.000000 0 /
kworker/30:1 18012 6234.935501 5 120 0.000000 0.026505 0.000000 0 /
CPU 3/KVM 73538 2789.628278 24788 120 0.000000 2802.924643 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu3
cpu#34, 2197.477 MHz
runnable tasks:
task PID tree-key switches prio wait-time sum-exec sum-sleep
----------------------------------------------------------------------------------------------------------
migration/34 204 0.000000 107 0 0.000000 89.067908 0.000000 0 /
ksoftirqd/34 205 -13.046824 3 120 0.000000 0.002884 0.000000 0 /
kworker/34:0 206 -12.922407 40 120 0.000000 0.127423 0.000000 0 /
kworker/34:0H 207 -9.320822 8 100 0.000000 0.017381 0.000000 0 /
kworker/34:1 18016 11315.391422 25 120 0.000000 0.196078 0.000000 0 /
qemu-kvm 73517 471.930276 30975 120 0.000000 1295.543576 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
CPU 0/KVM 73535 6160.062172 19201 120 0.000000 6174.260310 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/vcpu0
vnc_worker 73540 459.653524 38 120 0.000000 7.535037 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 78703 449.098251 2 120 0.000000 0.120313 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 78704 449.131175 3 120 0.000000 0.066961 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
worker 78705 461.100994 4 120 0.000000 0.022897 0.000000 0 /machine.slice/machine-qemu\x2d1\x2dinstance\x2d0000001d.scope/emulator
'%20d='M201.5%20305.5c-13.8%200-24.9-11.1-24.9-24.6%200-13.8%2011.1-24.9%2024.9-24.9%2013.6%200%2024.6%2011.1%2024.6%2024.9%200%2013.6-11.1%2024.6-24.6%2024.6zM504%20256c0%20137-111%20248-248%20248S8%20393%208%20256%20119%208%20256%208s248%20111%20248%20248zm-132.3-41.2c-9.4%200-17.7%203.9-23.8%2010-22.4-15.5-52.6-25.5-86.1-26.6l17.4-78.3%2055.4%2012.5c0%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.3%2024.9-24.9s-11.1-24.9-24.9-24.9c-9.7%200-18%205.8-22.1%2013.8l-61.2-13.6c-3-.8-6.1%201.4-6.9%204.4l-19.1%2086.4c-33.2%201.4-63.1%2011.3-85.5%2026.8-6.1-6.4-14.7-10.2-24.1-10.2-34.9%200-46.3%2046.9-14.4%2062.8-1.1%205-1.7%2010.2-1.7%2015.5%200%2052.6%2059.2%2095.2%20132%2095.2%2073.1%200%20132.3-42.6%20132.3-95.2%200-5.3-.6-10.8-1.9-15.8%2031.3-16%2019.8-62.5-14.9-62.5zM302.8%20331c-18.2%2018.2-76.1%2017.9-93.6%200-2.2-2.2-6.1-2.2-8.3%200-2.5%202.5-2.5%206.4%200%208.6%2022.8%2022.8%2087.3%2022.8%20110.2%200%202.5-2.2%202.5-6.1%200-8.6-2.2-2.2-6.1-2.2-8.3%200zm7.7-75c-13.6%200-24.6%2011.1-24.6%2024.9%200%2013.6%2011.1%2024.6%2024.6%2024.6%2013.8%200%2024.9-11.1%2024.9-24.6%200-13.8-11-24.9-24.9-24.9z'/%3e%3c/svg%3e){kind=small}