On 07/29/2010 03:47 PM, Alexander Graf wrote:
On PPC we run PR=0 (kernel mode) code in PR=1 (user mode) and don't use the hypervisor extensions.While that is all great to show that virtualization is possible, there are quite some cases where the emulation overhead of privileged instructions is killing performance. This patchset tackles exactly that issue. It introduces a paravirtual framework using which KVM and Linux share a page to exchange register state with. That way we don't have to switch to the hypervisor just to change a value of a privileged register. To prove my point, I ran the same test I did for the MMU optimizations against the PV framework. Here are the results: [without] debian-powerpc:~# time for i in {1..1000}; do /bin/echo hello> /dev/null; done real 0m14.659s user 0m8.967s sys 0m5.688s [with] debian-powerpc:~# time for i in {1..1000}; do /bin/echo hello> /dev/null; done real 0m7.557s user 0m4.121s sys 0m3.426s So this is a significant performance improvement! I'm quite happy how fast this whole thing becomes :) I tried to take all comments I've heard from people so far about such a PV framework into account. In case you told me something before that is a no-go and I still did it, please just tell me again. To make use of this whole thing you also need patches to qemu and openbios. I have them in my queue, but want to see this set upstream first before I start sending patches to the other projects. Now go and have fun with fast VMs on PPC! Get yourself a G5 on ebay and start experiencing the power yourself. - heh
Applied this and your follow on 7-part series, thanks. -- error compiling committee.c: too many arguments to function _______________________________________________ Linuxppc-dev mailing list Linuxppc-dev@lists.ozlabs.org https://lists.ozlabs.org/listinfo/linuxppc-dev
