我想知道一些性能问题。我在实施方面遇到了一些问题，但这不是我当前的重点。我为我的女儿们建造了一台电脑，让她们同时玩《我的世界》。为了实现这一点，我使用 Linux KVM。客人使用的是Windows 10。
我通过两种方式完成此操作，一种使用 CLI，一种使用 virt-manager。
CLI版本如下
qemu-system-x86_64 -enable-kvm -M q35 -m 3072 -cpu host \
-smp 2,sockets=1,cores=2,threads=1 \
-bios /usr/share/qemu/bios.bin -vga none \
-device virtio-scsi-pci,id=scsi \
-drive file=/srv/wip.img,format=raw,id=disk,if=none,cache=none,aio=native \
-device scsi-hd,drive=disk \
-cdrom /home/driz/win10.iso \
-device ioh3420,bus=pcie.0,addr=1c.0,multifunction=on,port=1,chassis=1,id=root.1 \
-device vfio-pci,host=01:00.0,bus=root.1,addr=00.0,multifunction=on,x-vga=on \
-device virtio-net-pci,mac=52:54:00:ea:c8:8d \
-usb -usbdevice host:040b:2000 -usbdevice host:046d:c01e -usbdevice host:0d8c:0014 \
-boot menu=on
我们现在可以忽略显卡直通和 USB 直通（除非它们是因素）。假设我正确理解了我在这里所做的事情，我有一个 virtio scsi 控制器和一个使用原始存储连接到它的 scsi 磁盘。我安装了一张 CD 来安装 Windows 10（在安装过程中我使用 qemu 窗口将其交换为磁盘的 virtio 驱动程序）。此安装需要很长时间并且磁盘性能似乎很差。实际的 Windows 安装大约需要 20 分钟。
另一方面，在 virt-manager 中创建机器，使用我认为相同的设置（下面是我从 ps 获取的命令行）
qemu-system-x86_64 -enable-kvm -name guest=win10,debug-threads=on -S \
-object secret,id=masterKey0,format=raw,file=/var/lib/libvirt/qemu/domain-2-win10/master-key.aes \
-machine pc-q35-2.6,accel=kvm,usb=off \
-cpu host,hv_time,hv_relaxed,hv_vapic,hv_spinlocks=0x1fff \
-drive file=/srv/ovmf-x64/OVMF_CODE-pure-efi.fd,if=pflash,format=raw,unit=0,readonly=on \
-drive file=/var/lib/libvirt/qemu/nvram/win10_VARS.fd,if=pflash,format=raw,unit=1 \
-m 3072 -realtime mlock=off -smp 1,maxcpus=2,sockets=1,cores=1,threads=2 \
-uuid 6529c02d-b03f-4adf-8cbf-58dc9227e976 -no-user-config -nodefaults \
-chardev socket,id=charmonitor,path=/var/lib/libvirt/qemu/domain-2-win10/monitor.sock,server,nowait \
-mon chardev=charmonitor,id=monitor,mode=control \
-rtc base=localtime,driftfix=slew \
-global kvm-pit.lost_tick_policy=discard -no-hpet -no-shutdown \
-global ICH9-LPC.disable_s3=1 \
-global ICH9-LPC.disable_s4=1 \
-boot strict=on \
-device i82801b11-bridge,id=pci.1,bus=pcie.0,addr=0x1e \
-device pci-bridge,chassis_nr=2,id=pci.2,bus=pci.1,addr=0x0 \
-device ich9-usb-ehci1,id=usb,bus=pcie.0,addr=0x1d.0x7 \
-device ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pcie.0,multifunction=on,addr=0x1d \
-device ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pcie.0,addr=0x1d.0x1 \
-device ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pcie.0,addr=0x1d.0x2 \
-device virtio-scsi-pci,id=scsi0,bus=pci.2,addr=0x3 \
-device virtio-serial-pci,id=virtio-serial0,bus=pci.2,addr=0x4 \
-drive file=/srv/wip.img,format=raw,if=none,id=drive-scsi0-0-0-0,cache=none,aio=native \
-device scsi-hd,bus=scsi0.0,channel=0,scsi-id=0,lun=0,drive=drive-scsi0-0-0-0,id=scsi0-0-0-0,bootindex=1 \
-drive file=/srv/win10.iso,format=raw,if=none,media=cdrom,id=drive-sata0-0-1,readonly=on \
-device ide-cd,bus=ide.1,drive=drive-sata0-0-1,id=sata0-0-1 \
-drive file=/srv/virtio-win.iso,format=raw,if=none,media=cdrom,id=drive-sata0-0-2,readonly=on \
-device ide-cd,bus=ide.2,drive=drive-sata0-0-2,id=sata0-0-2 \
-netdev tap,fd=26,id=hostnet0 \
-device virtio-net-pci,netdev=hostnet0,id=net0,mac=52:54:00:2b:38:74,bus=pci.2,addr=0x1 -chardev pty,id=charserial0 \
-device isa-serial,chardev=charserial0,id=serial0 \
-chardev spicevmc,id=charchannel0,name=vdagent \
-device virtserialport,bus=virtio-serial0.0,nr=1,chardev=charchannel0,id=channel0,name=com.redhat.spice.0 \
-device usb-tablet,id=input0,bus=usb.0,port=1 \
-spice port=5900,addr=127.0.0.1,disable-ticketing,image-compression=off,seamless-migration=on \
-device qxl-vga,id=video0,ram_size=67108864,vram_size=67108864,vram64_size_mb=0,vgamem_mb=16,max_outputs=1,bus=pcie.0,addr=0x1 \
-device intel-hda,id=sound0,bus=pci.2,addr=0x2 \
-device hda-duplex,id=sound0-codec0,bus=sound0.0,cad=0 \
-chardev spicevmc,id=charredir0,name=usbredir \
-device usb-redir,chardev=charredir0,id=redir0,bus=usb.0,port=2 \
-chardev spicevmc,id=charredir1,name=usbredir \
-device usb-redir,chardev=charredir1,id=redir1,bus=usb.0,port=3 \
-device virtio-balloon-pci,id=balloon0,bus=pci.2,addr=0x5 \
-msg timestamp=on
windows 大约需要 7 分钟即可安装完毕。在这两种情况下，原始磁盘映像都是使用 dd 全新创建的，大小和规格相同。在这两种情况下，我都通过命令行上的 dd 创建它（而不是使用 virt-manager） 我的问题是，为什么使用 virt-manager 构建与我的 CLI 构建相比安装速度要快得多。我看到 virt-manager 设置中有一些额外的控制器，但这对我来说确实没有意义。我看到的主要区别是 CLI 上的顶级场景是 seabios，virt-manager 构建是 uefi。奇怪的是，在 Windows 启动过程中，通常 uefi 会显示制造商的徽标，但我看到 Windows 徽标，就好像这是 BIOS 启动一样。也许这是因为它是虚拟的，但我希望在 Windows 启动过程中看到 tiano 徽标，因为它是 uefi。
由于 virsh 的 xml 可能会显示更多信息，因此我将其附加在下面
<domain type='kvm' id='2'>
<name>win10</name>
<uuid>6529c02d-b03f-4adf-8cbf-58dc9227e976</uuid>
<memory unit='KiB'>3145728</memory>
<currentMemory unit='KiB'>3145728</currentMemory>
<vcpu placement='static' current='1'>2</vcpu>
<resource>
<partition>/machine</partition>
</resource>
<os>
<type arch='x86_64' machine='pc-q35-2.6'>hvm</type>
<loader readonly='yes' type='pflash'>/srv/ovmf-x64/OVMF_CODE-pure-efi.fd</loader>
<nvram>/var/lib/libvirt/qemu/nvram/win10_VARS.fd</nvram>
<boot dev='hd'/>
</os>
<features>
<acpi/>
<apic/>
<hyperv>
<relaxed state='on'/>
<vapic state='on'/>
<spinlocks state='on' retries='8191'/>
</hyperv>
</features>
<cpu mode='host-passthrough'>
<topology sockets='1' cores='1' threads='2'/>
</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>restart</on_crash>
<pm>
<suspend-to-mem enabled='no'/>
<suspend-to-disk enabled='no'/>
</pm>
<devices>
<emulator>/usr/bin/kvm-spice</emulator>
<disk type='file' device='disk'>
<driver name='qemu' type='raw' cache='none' io='native'/>
<source file='/srv/wip.img'/>
<backingStore/>
<target dev='sda' bus='scsi'/>
<alias name='scsi0-0-0-0'/>
<address type='drive' controller='0' bus='0' target='0' unit='0'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/srv/win10.iso'/>
<backingStore/>
<target dev='sdb' bus='sata'/>
<readonly/>
<alias name='sata0-0-1'/>
<address type='drive' controller='0' bus='0' target='0' unit='1'/>
</disk>
<disk type='file' device='cdrom'>
<driver name='qemu' type='raw'/>
<source file='/srv/virtio-win.iso'/>
<backingStore/>
<target dev='sdc' bus='sata'/>
<readonly/>
<alias name='sata0-0-2'/>
<address type='drive' controller='0' bus='0' target='0' unit='2'/>
</disk>
<controller type='usb' index='0' model='ich9-ehci1'>
<alias name='usb'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x7'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci1'>
<alias name='usb'/>
<master startport='0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x0' multifunction='on'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci2'>
<alias name='usb'/>
<master startport='2'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x1'/>
</controller>
<controller type='usb' index='0' model='ich9-uhci3'>
<alias name='usb'/>
<master startport='4'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1d' function='0x2'/>
</controller>
<controller type='scsi' index='0' model='virtio-scsi'>
<alias name='scsi0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x03' function='0x0'/>
</controller>
<controller type='sata' index='0'>
<alias name='ide'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1f' function='0x2'/>
</controller>
<controller type='pci' index='0' model='pcie-root'>
<alias name='pcie.0'/>
</controller>
<controller type='pci' index='1' model='dmi-to-pci-bridge'>
<model name='i82801b11-bridge'/>
<alias name='pci.1'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x1e' function='0x0'/>
</controller>
<controller type='pci' index='2' model='pci-bridge'>
<model name='pci-bridge'/>
<target chassisNr='2'/>
<alias name='pci.2'/>
<address type='pci' domain='0x0000' bus='0x01' slot='0x00' function='0x0'/>
</controller>
<controller type='virtio-serial' index='0'>
<alias name='virtio-serial0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x04' function='0x0'/>
</controller>
<interface type='direct'>
<mac address='52:54:00:2b:38:74'/>
<source dev='enp0s31f6' mode='bridge'/>
<target dev='macvtap0'/>
<model type='virtio'/>
<alias name='net0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x01' function='0x0'/>
</interface>
<serial type='pty'>
<source path='/dev/pts/2'/>
<target port='0'/>
<alias name='serial0'/>
</serial>
<console type='pty' tty='/dev/pts/2'>
<source path='/dev/pts/2'/>
<target type='serial' port='0'/>
<alias name='serial0'/>
</console>
<channel type='spicevmc'>
<target type='virtio' name='com.redhat.spice.0' state='disconnected'/>
<alias name='channel0'/>
<address type='virtio-serial' controller='0' bus='0' port='1'/>
</channel>
<input type='tablet' bus='usb'>
<alias name='input0'/>
<address type='usb' bus='0' port='1'/>
</input>
<input type='mouse' bus='ps2'>
<alias name='input1'/>
</input>
<input type='keyboard' bus='ps2'>
<alias name='input2'/>
</input>
<graphics type='spice' port='5900' autoport='yes' listen='127.0.0.1'>
<listen type='address' address='127.0.0.1'/>
<image compression='off'/>
</graphics>
<sound model='ich6'>
<alias name='sound0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x02' function='0x0'/>
</sound>
<video>
<model type='qxl' ram='65536' vram='65536' vgamem='16384' heads='1' primary='yes'/>
<alias name='video0'/>
<address type='pci' domain='0x0000' bus='0x00' slot='0x01' function='0x0'/>
</video>
<redirdev bus='usb' type='spicevmc'>
<alias name='redir0'/>
<address type='usb' bus='0' port='2'/>
</redirdev>
<redirdev bus='usb' type='spicevmc'>
<alias name='redir1'/>
<address type='usb' bus='0' port='3'/>
</redirdev>
<memballoon model='virtio'>
<alias name='balloon0'/>
<address type='pci' domain='0x0000' bus='0x02' slot='0x05' function='0x0'/>
</memballoon>
</devices>
<seclabel type='dynamic' model='apparmor' relabel='yes'>
<label>libvirt-6529c02d-b03f-4adf-8cbf-58dc9227e976</label>
<imagelabel>libvirt-6529c02d-b03f-4adf-8cbf-58dc9227e976</imagelabel>
</seclabel>
<seclabel type='dynamic' model='dac' relabel='yes'>
<label>+110:+111</label>
<imagelabel>+110:+111</imagelabel>
</seclabel>
</domain>