qemu really slow with kvm cpu and 9x guest. Help!

Holering · 05-21-2014, 06:21 PM

Compiled quemu-2.0 from slackbuilds.org 14.1 slackbuild. If I run DOS, I get 100% cpu usage (whether idle or running something). Running Doom game doesn't reduce 100% cpu usage (have to make viewable screen minimum size in Doom)! Changing cpu and/or disabling kvm doesn't solve this. Qemu doesn't seem to be running properly...

Code:

bash-4.2# lsmod | grep kvm
kvm_amd                40288  0 
kvm                   218524  1 kvm_amd

shows kvm and kvm_amd modules loaded (using piledriver cpu with AMD virtualization enabled).

VirtualBox has none of these problems.

Help with this would be greatly appreciated!

allend · 05-21-2014, 07:39 PM

I have seen this running Windows98 in a virtual machine. It is because the virtualised operating system does not implement the CPU halt instruction. You can add a program to Windows98 that will do this (google for rain20.zip).

I suggest that you create a virtual Windows98 (the last version of Windows with a genuine DOS shell) and try with that.

This thread seems relevant to your problem. http://www.linuxquestions.org/questi...es-4175485852/

jefro · 05-21-2014, 07:59 PM

Not sure why I think this but I was pretty sure in the qemu console one could issue the hlt command or maybe from start up script.

But, as above, it is the hlt or halt problem.

I think vmware has a dos idle that you can add to the client.

Not sure if kvm has this same issue unless you don't have full hardware support. ??? dunno.

Holering · 05-23-2014, 01:28 AM

Downloaded and installed amnhlt.zip and it does reduce CPU usage from 100%. Still have the same terrible performance though. Everything is slow and choppy in 9x and DOS. Actually, if I avoid KVM I get much better performance, although nowhere near where it should be; it runs like a pentium instead of a 286.

jefro · 05-23-2014, 03:31 PM

I'd think that your system is running in emulation rather than hardware vm supported.

"VirtualBox has none of these problems."
This is a more mature product. Qemu is not much more than a hobby copy of a hobby vm of bochs. It may be that you don't have kvm set up to use (forgot name) module or service.