[Qemu-devel] Linux CPU accouting with kqemu

[Steve Fosdick]

I have noticed that the Linux system CPU usage seems remarkably high 
when running Windows XP as a guest under qemu/kqemu, but not when 
running under qemu without kqemu.

Just today I was reading the kqemu API documentation and it occurred to 
be that from the Linux perspective the user/system CPU times may be 
backward with kqemu.

Is it perhaps the case that when kqemu has been told to run code in the 
guest VM (KQEMU_EXEC ioctl) and this is happenning without any 
exceptions (more likely when the guest is running user-mode code rather 
than OS code) Linux still sees this as running in the kernel and 
records it as "system" time but when kqemu returns to qemu (because of 
an exception) the Linux kernel now sees this as user CPU time when in 
all likelihood the guest OS is now executing somewhere it it's kernel?

Regards,
Steve.