无法获取libvirt域的所有内存统计信息

我遇到了虚拟机（guest Windows 7，x86_64）的一些问题，在qemu-kvm下运行并由libvirt管理（主要是从virt-manager创建并运行） . 问题是我无法通过运行获得完整的内存统计信息

virsh -c qemu:///system dommemstat win7

或者通过致电

virDomainMemoryStats(...)

从c代码（据我所知，或多或少相同的事情） . 我还从libvirt aplication dev guide测试了libvirt第35个例子 . 这真的让我感到担忧，因为我现在正在项目下工作，旨在为vm自动设置最佳内存大小，因此我需要在我的代码中使用它们 .

我从virsh获得的唯一输出是

actual 4194304
last_update 1500404513
rss 4161676

在搜索网络后，我发现这些是统计数据，libvirt可以在不应用于不断膨胀的驱动程序的情况下获得这些数据 . 但是我已经在Windows中安装了VirtIO气球驱动程序，系统声称它正在运行 . 我真的不知道，如何找出qemu是否意识到这一点（为你的想法打开） .

另外我发现我需要在系统xml中设置统计周期，我已经做过了，并没有给出任何结果 . 我还发现qemu使用了一些“qom-get”脚本来实际测量统计数据，但我无法使用它

virsh # qemu-monitor-command 1 --hmp "qom-get"

（输出那个命令是未知的）我在PATH中看不到它 . 此外 pacman -Fo qom-get 和 pkgfile qom-get 什么都没有 . 我的主机系统是Arch Linux . win7.xml的内容是

<domain type='kvm'>
  <name>win7</name>
  <uuid>438145c1-a2df-4c86-96d6-2bf7b379d70b</uuid>
  <memory unit='KiB'>4194304</memory>
  <currentMemory unit='KiB'>4194304</currentMemory>
  <vcpu placement='static' current='2'>4</vcpu>
  <os>
    <type arch='x86_64' machine='pc-i440fx-2.9'>hvm</type>
    <boot dev='hd'/>
  </os>
  <features>
    <acpi/>
    <apic/>
    <hyperv>
      <relaxed state='on'/>
      <vapic state='on'/>
      <spinlocks state='on' retries='8191'/>
    </hyperv>
    <vmport state='off'/>
  </features>
  <cpu mode='custom' match='exact' check='partial'>
    <model fallback='allow'>Broadwell-noTSX</model>
  </cpu>
  <clock offset='localtime'>
    <timer name='rtc' tickpolicy='catchup'/>
    <timer name='pit' tickpolicy='delay'/>
    <timer name='hpet' present='no'/>
    <timer name='hypervclock' present='yes'/>
  </clock>
  <on_poweroff>destroy</on_poweroff>
  <on_reboot>restart</on_reboot>
  <on_crash>destroy</on_crash>
  <pm>
    <suspend-to-mem enabled='no'/>
    <suspend-to-disk enabled='no'/>
  </pm>
  <devices>
    <emulator>/usr/sbin/qemu-system-x86_64</emulator>
    <disk type='file' device='disk'>
      <driver name='qemu' type='qcow2'/>
      <source file='/var/lib/libvirt/images/win7.qcow2'/>
      <target dev='hda' bus='ide'/>
      <address type='drive' controller='0' bus='0' target='0' unit='0'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <target dev='hdb' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='0' target='0' unit='1'/>
    </disk>
    <disk type='file' device='cdrom'>
      <driver name='qemu' type='raw'/>
      <source file='/usr/share/virtio/virtio-win.iso'/>
      <target dev='hdc' bus='ide'/>
      <readonly/>
      <address type='drive' controller='0' bus='1' target='0' unit='0'/>
    </disk>
    <controller type='usb' index='0' model='ich9-ehci1'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x7'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci1'>
      <master startport='0'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x0' multifunction='on'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci2'>
      <master startport='2'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x1'/>
    </controller>
    <controller type='usb' index='0' model='ich9-uhci3'>
      <master startport='4'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x05' function='0x2'/>
    </controller>
    <controller type='pci' index='0' model='pci-root'/>
    <controller type='ide' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x1'/>
    </controller>
    <controller type='virtio-serial' index='0'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x06' function='0x0'/>
    </controller>
    <interface type='network'>
      <mac address='52:54:00:9d:4e:85'/>
      <source network='default'/>
      <model type='rtl8139'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x03' function='0x0'/>
    </interface>
    <serial type='pty'>
      <target port='0'/>
    </serial>
    <console type='pty'>
      <target type='serial' port='0'/>
    </console>
    <channel type='spicevmc'>
      <target type='virtio' name='com.redhat.spice.0'/>
      <address type='virtio-serial' controller='0' bus='0' port='1'/>
    </channel>
    <input type='tablet' bus='usb'>
      <address type='usb' bus='0' port='1'/>
    </input>
    <input type='mouse' bus='ps2'/>
    <input type='keyboard' bus='ps2'/>
    <graphics type='spice' autoport='yes'>
      <listen type='address'/>
      <image compression='off'/>
    </graphics>
    <sound model='ich6'>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x04' function='0x0'/>
    </sound>
    <video>
      <model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x02' function='0x0'/>
    </video>
    <redirdev bus='usb' type='spicevmc'>
      <address type='usb' bus='0' port='2'/>
    </redirdev>
    <redirdev bus='usb' type='spicevmc'>
      <address type='usb' bus='0' port='3'/>
    </redirdev>
    <memballoon model='virtio'>
      <stats period='10'/>
      <address type='pci' domain='0x0000' bus='0x00' slot='0x07' function='0x0'/>
    </memballoon>
  </devices>
</domain>

我肯定错过了什么，但我看不清楚 . 有人可以，给我任何有用的链接或指南吗？我真的很感激 .

这是question on Arch Linux newbie forum的副本 . 如果有人会给出相应的答案，我会与其他网站分享 .

================================================

UPD . 气球正在工作：我可以做这样的事情

virsh # qemu-monitor-command win7 --hmp "info balloon"
balloon: actual=4096
virsh # qemu-monitor-command win7 --hmp "balloon 2048"
virsh # qemu-monitor-command win7 --hmp "info balloon"
balloon: actual=2048

但qom-get不会这样做：

virsh # qemu-monitor-command windows7 '{ "execute": "qom-get",  "arguments": { "path": "/machine/peripheral/balloon0",  "property": "guest-stats" } }'
{"return":{"stats":{"stat-swap-out":-1,"stat-available-memory":-1,"stat-free-memory":-1,"stat-minor-faults":-1,"stat-major-faults":-1,"stat-total-memory":-1,"stat-swap-in":-1},"last-update":1500639136},"id":"libvirt-396"}

非常感谢帮助 .