我在使用 qemu-kvm 并由 libvirt 管理的虚拟机（guest windows 7、x86_64）时遇到了一些问题（主要从 virt-manager 创建和运行）。问题是我无法从运行中获得完整的内存统计信息
virsh -c qemu:///system dommemstat win7
或通过调用
virDomainMemoryStats(...)
来自 c++ 代码（据我所知，这或多或少是相同的东西）。我还测试了libvirt aplication dev guide中的 libvirt 35th example 。这真的让我很担心，因为现在我正在项目下工作，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 得到的唯一输出是
actual 4194304
last_update 1500404513
rss 4161676
在网上搜索后，我发现这些是统计数据，libvirt 可以在不应用气球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，并且系统声称它正在运行。我真的不知道，如何找出 qemu 是否知道它（为您的想法开放）。
另外我发现我需要在系统 xml 中设置统计周期，我已经这样做了，但什么也没给出。我还发现 qemu 使用一些“qom-get”脚本来实际测量统计数据，但我不能从
virsh # qemu-monitor-command 1 --hmp "qom-get"
（输出该命令未知）并且我在 PATH 中看不到它。也pacman -Fo qom-get什么pkgfile qom-get都不给。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>
我肯定错过了一些东西，但我看不到什么。谁能给我任何有用的链接或指南？我真的很感激。
这是Arch Linux 新手论坛上问题的重复。如果有人会给出适当的答案，我会与其他网站分享。
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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
但是 qom-get 不会：
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"}
帮助将不胜感激。