[Qemu-devel] CPU Benchmark qemu-kvm 1.2.0 Win XP vs. Win 7

[Erik Rull]

Hi all,

when testing my first Windows 7 guest, I noticed, that the IRQ load / 
kernel time within the guest is quite high when having network access. I 
use the virtio drivers - the same version as in the Windows XP guests. 
There the kernel load is nearly only 50% of the Win7 load. Why? The 
provided guest hardware is exactly the same... Win XP was used without 
ACPI, Win7 requires it - so it is enabled on both commandlines. But I can't 
imagine that this causes such a huge performance drop.

Additionally I did some CPU benchmarking and the Win7 guest results in ~ 
20% less in the hard/wetstone performance. Also the harddisk access is slower.

Any ideas what may cause the pure hardware performance degradation between 
these two guests when having the same qemu-kvm hardware parameters (beside 
the image file of course)? Any hints what to do to improve the performance 
for Win7 would be appreciated.

I would at least assume that the pure CPU performance would not drop 
significantly.

Thanks.

Best regards,

Erik