Very wrong cpu info in qemu/kvm

[Gameborn]

I have installed windows 10 on kvm using virt-manager with host os arch Linux and made integrated graphics passsthrough and it worked, but.

Cpu performance is bad and it decets cpu model uncorrectly. If I enable "copy host cpu info" it enable cpu model amd opteron g5, while my actual is a10-7850k on kaveri architecture. this is what guest sees cpu like this and it's only single core, dispite selecting 4 cores:

please help, gpu performance is near-native but cpu is very low. It much slower than virtualbox or VMware.

 

Sorry for messy explanation, my English is very bad.

[SCHISCHKA]

My comes up as opteron too, I never looked into it.

It's likely the settings you have it as 4 sockets, not 4 cores. If this is correct it should not be difficult to correct it. If you are using windows Home it won't work on more than one socket, I dont know if pro or ent has a limit.

[Gameborn]

5 minutes ago, SCHISCHKA said:

My comes up as opteron too, I never looked into it.

It's likely the settings you have it as 4 sockets, not 4 cores. If this is correct it should not be difficult to correct it. If you are using windows Home it won't work on more than one socket, I dont know if pro or ent has a limit.

i'm running windows 10 home and it detects that it's running in vm. in task manager in cpu section it shows: sockets: 1, virtual machine: yes, virtual processors: 1

[SCHISCHKA]

2 minutes ago, Gameborn said:

i'm running windows 10 home and it detects that it's running in vm. in task manager in cpu section it shows: sockets: 1, virtual machine: yes, virtual processors: 1

theres your problem. change your settings so its 4 cores not 4 sockets. The windows Home license and technology restrictions dont give you much to play with, thats why its cheaper.

[Gameborn]

2 hours ago, SCHISCHKA said:

theres your problem. change your settings so its 4 cores not 4 sockets. The windows Home license and technology restrictions dont give you much to play with, thats why its cheaper.

it is four cores not four sockets. It was by default, but I changed it to 1 socket and 4 cores aswell as allocating four cores all time but that isn't the problem. Cpu load is still often at 100% and system is choppy because of this.

[unijab]

drivers?

 

[Gameborn]

2 minutes ago, unijab said:

drivers?

 

which one? arch distro, gt210 with nvidia-340xx drivers for host and integrated r7 graphics passthtough to vm. Latest version of all packages, linux kernel 4.10.13. Latest amd drivers on windows guest. Linux radeon drivers are blacklisted and iommu is loaded properly.

[unijab]

For windows.... begin here?

 

https://www.linux-kvm.org/page/WindowsGuestDrivers/Download_Drivers

https://fedoraproject.org/wiki/Windows_Virtio_Drivers

[Gameborn]

Just now, unijab said:

For windows.... begin here?

 

https://www.linux-kvm.org/page/WindowsGuestDrivers/Download_Drivers

https://fedoraproject.org/wiki/Windows_Virtio_Drivers

 i installed most of them but none of them are something to do with cpu.

that's what they include:

Spoiler

• NetKVM/: Virtio Network driver
• viostor/: Virtio Block driver
• vioscsi/: Virtio SCSI driver
• viorng/: Virtio RNG driver
• vioser/: Virtio serial driver
• Balloon/: Virtio Memory Balloon driver
• qxl/: QXL graphics driver for Windows 7 and earlier. (build virtio-win-0.1.103-1 and later)
• qxldod/: QXL graphics driver for Windows 8 and later. (build virtio-win-0.1.103-2 and later)
• pvpanic/: QEMU pvpanic device driver (build virtio-win-0.1.103-2 and later)
• guest-agent/: QEMU Guest Agent 32bit and 64bit MSI installers
• qemupciserial/: QEMU PCI serial device driver
• *.vfd: VFD floppy images for using during install of Windows XP

 

[Sauron]

On 5/6/2017 at 1:57 PM, Gameborn said:

it is four cores not four sockets. It was by default, but I changed it to 1 socket and 4 cores aswell as allocating four cores all time but that isn't the problem. Cpu load is still often at 100% and system is choppy because of this.

when running kvm you can't pass ALL your cores to the vm - the host still needs at least one core to run. try 1 socket 3 cores.

[Gameborn]

Just now, Sauron said:

when running kvm you can't pass ALL your cores to the vm - the host still needs at least one core to run. try 1 socket 3 cores.

I tried with two cores and balancing some others settings - performs WAY better, but I thing 16mb of l3 is the problem it still works better with four cores because of tweaks that I made. But still, I can't disable l3 cache (it detects 16mb). <cache level='3' mode='disable'/> returns error that it's bad parameter, while I copied all cpu config straight from red hat wiki.

[Sauron]

9 minutes ago, Gameborn said:

I tried with two cores and balancing some others settings - performs WAY better, but I thing 16mb of l3 is the problem it still works better with four cores because of tweaks that I made. But still, I can't disable l3 cache (it detects 16mb). <cache level='3' mode='disable'/> returns error that it's bad parameter, while I copied all cpu config straight from red hat wiki.

It may be a cpu specific restriction, what kind of problems do you get now? Does it still perform below your expectations or is it something else?

[Gameborn]

Just now, Sauron said:

It may be a cpu specific restriction, what kind of problems do you get now? Does it still perform below your expectations or is it something else?

I tried running league of legends, iGPU load is at around ~60%, cpu is 40-70% on all four cores, but huge fps drops and some stuttering while more geometry is happening.

I suppose that it's because of 16mb virtualized l3 cache, my host cpu doesn't have it. As I know, l3 cache is accesed more often because of it's potential speed on cpu's, but most likely it stores it in ram and obviously it's way slower.

[Sauron]

7 minutes ago, Gameborn said:

I tried running league of legends, iGPU load is at around ~60%, cpu is 40-70% on all four cores, but huge fps drops and some stuttering while more geometry is happening.

I suppose that it's because of 16mb virtualized l3 cache, my host cpu doesn't have it. As I know, l3 cache is accesed more often because of it's potential speed on cpu's, but most likely it stores it in ram and obviously it's way slower.

could you link the instructions you followed?

[Gameborn]

Just now, Sauron said:

could you link the instructions you followed?

here is instructions that I followed to passthrough my integrated graphics to vm:

https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVMF

gt210 is used for host.

 

[Sauron]

3 minutes ago, Gameborn said:

here is instructions that I followed to passthrough my integrated graphics to vm:

https://wiki.archlinux.org/index.php/PCI_passthrough_via_OVMF

gt210 is used for host.

 

is this you? https://bbs.archlinux.org/viewtopic.php?id=225913

 

If it is, I noticed the config file you posted there mentions "16384" of vram - if that's in MB that doesn't sound right. Have you checked how the gpu is recognized by windows? If it's trying to use more vram than is actually there (in this case, that would be system memory and it would cache on the storage drive) it might cause the problems you're experiencing.

 

I also can't find any reference to the "cache level" options on the arch or rh wiki. Where did you read that?

[Gameborn]

1 minute ago, Sauron said:

is this you? https://bbs.archlinux.org/viewtopic.php?id=225913

 

If it is, I noticed the config file you posted there mentions "16384" of vram - if that's in MB that doesn't sound right. Have you checked how the gpu is recognized by windows? If it's trying to use more vram than is actually there (in this case, that would be system memory and it would cache on the storage drive) it might cause the problems you're experiencing.

 

I also can't find any reference to the "cache level" options on the arch or rh wiki. Where did you read that?

yes, this is my post.

16000 is in kilobytes, and this is for virtual display device that is being used when virtual uefi starts. When windows boots up, I takes control over and disables it (virtual uefi don't  work with gpu passthrough for some reason). 

I took cache config from libvirt wiki: https://libvirt.org/formatdomain.html

[Sauron]

8 minutes ago, Gameborn said:

yes, this is my post.

16000 is in kilobytes, and this is for virtual display device that is being used when virtual uefi starts. When windows boots up, I takes control over and disables it (virtual uefi don't  work with gpu passthrough for some reason). 

I took cache config from libvirt wiki: https://libvirt.org/formatdomain.html

try substituting that option with

<cache mode='passthrough'/>

without specifying any level. In theory this should let the library detect and pass through the available cache - and nothing else.

[Gameborn]

Just now, Sauron said:

try substituting that option with

<cache mode='passthrough'/>

without specifying any level. In theory this should let the library detect and pass through the available cache - and nothing else.

I alredy tried that, virsh says that it's bad cpu parameter and if forced removes this line.

[Gameborn]

14 minutes ago, Sauron said:

try substituting that option with

<cache mode='passthrough'/>

without specifying any level. In theory this should let the library detect and pass through the available cache - and nothing else.

there is now cache options at all in domain.rng which is used like template

[Sauron]

16 minutes ago, Gameborn said:

I alredy tried that, virsh says that it's bad cpu parameter and if forced removes this line.

 

2 minutes ago, Gameborn said:

there is now cache options at all in domain.rng which is used like template

Are you sure you have the latest version of libvirt? Try the other cpu modes to see if that makes any difference at all, if it doesn't I don't know what the problem could be - you'd have to open a bug report for libvirt. It's possible it's just bugged and doesn't support your cpu correctly.