[Qemu-discuss] The difference between qemu-kvm-1.2.0 & qemu-1.5.1

[Yaodong Yang]

Hi everyone,

Previously, I used the qemu-kvm-1.2.0 from (http://www.linux-kvm.org/page/Downloads), and it worked well in my ubuntu server. Later, I found that some of the implementation(qemu-kvm-1.2.0) is out of date, so that I changed to qemu-1.5.1 (http://wiki.qemu.org/Download). I found that installing a guest ubuntu vm (qcow2 backup images) in qemu-1.5.1 is much slower than that in qemu-kvm-1.2.0. 

So could someone tell me the differences between them? particularly why the qemu-1.5.1 is slower than the qemu-kvm-1.2.0.  

I would like to implement something in the io path. My platform is a x86 64bit server, and my host os is ubuntu 12.04 desktop, 64 bits.

Thanks!

Yaodong