[Qemu-discuss] Performance problems with a single game

[Dennis Birkholz]

Hi list,

I use qemu/kvm on Gentoo Linux to run a Windows 7 VM for gaming. I use
vfio pass thought so my NVidia GTX 970 is available inside the VM. I
have an Intel i7-4790K with 16 GB RAM and use the build in i915 graphics
card as my primary (linux) output.

Inside the VM, most games run at nearly native speed (e.g. Battlefield 4
@ 2560x1440 and near max details ~ 55 frames). But the Neverwinter MMO
by Cryptic (http://playneverwinter.com) just gets about 8-15 frames
regardless which details and resolution I set.

Can someone guide me how to debug this problem so the devs can fix this
issue?

Thanks,
Dennis

Qemu command line: (I use the e1000 network intentional, virtio network
has the same game performance problem)
/usr/bin/qemu-system-x86_64 -name gaming-win7 -S -machine
pc-i440fx-2.3,accel=kvm,usb=off -cpu
Haswell,+abm,+pdpe1gb,+rdrand,+f16c,+osxsave,+pdcm,+xtpr,+tm2,+est,+vmx,+ds_cpl,+monitor,+dtes64,+pbe,+tm,+ht,+ss,+acpi,+ds,+vme,kvm=off
-m 8192 -realtime mlock=off -smp 6,sockets=1,cores=3,threads=2 -uuid
c3caad5a-5bf3-4417-b160-252ab130a560 -nographic -no-user-config
-nodefaults -chardev
socket,id=charmonitor,path=/var/lib/libvirt/qemu/gaming-win7.monitor,server,nowait
-mon chardev=charmonitor,id=monitor,mode=control -rtc base=localtime
-no-shutdown -global PIIX4_PM.disable_s3=1 -global PIIX4_PM.disable_s4=1
-boot strict=on -device ich9-usb-ehci1,id=usb,bus=pci.0,addr=0x5.0x7
-device
ich9-usb-uhci1,masterbus=usb.0,firstport=0,bus=pci.0,multifunction=on,addr=0x5
-device
ich9-usb-uhci2,masterbus=usb.0,firstport=2,bus=pci.0,addr=0x5.0x1
-device
ich9-usb-uhci3,masterbus=usb.0,firstport=4,bus=pci.0,addr=0x5.0x2
-device virtio-scsi-pci,id=scsi0,bus=pci.0,addr=0x4 -device
ahci,id=ahci0,bus=pci.0,addr=0x6 -drive
file=/dev/sda,if=none,id=drive-virtio-disk0,format=raw,cache=none,aio=native
-device
virtio-blk-pci,scsi=off,bus=pci.0,addr=0x7,drive=drive-virtio-disk0,id=virtio-disk0,bootindex=1
-drive
file=/var/lib/libvirt/images/virtio-win-0.1-100.iso,if=none,media=cdrom,id=drive-sata0-0-1,readonly=on,format=raw,cache=none
-device ide-cd,bus=ahci0.1,drive=drive-sata0-0-1,id=sata0-0-1 -netdev
tap,fd=19,id=hostnet0 -device
e1000,netdev=hostnet0,id=net0,mac=52:54:00:55:a4:0a,bus=pci.0,addr=0x2
-device AC97,id=sound0,bus=pci.0,addr=0x3 -device
virtio-balloon-pci,id=balloon0,bus=pci.0,addr=0x9 -vga none -device
vfio-pci,host=01:00.0,x-vga=on -device vfio-pci,host=01:00.1 -msg
timestamp=on