张磊强 <leiqzh...@gmail.com> wrote on 07/04/2013 07:10:24 PM:
> > HI, Abel & Stefan: > > After thinking twice about the benchmarks and the idea of > dataplane, I am still confused. Please note while I am familiar with the documentation and architecture of dataplane, I didn't contribute to the dataplane code. So Stefan is actually the right person to answer your questions. > It's my understanding that the advantage of dataplane mainly > includes two parts. The first is that splitting the IO thread from > vcpu thread will avoid the global mutex competition, and the second > is that the individual IO thread will not be blocked when "vm exit" > occurs in vcpu thread. Am I right? As far as I understand you are right. But wait for Stefan's confirmation. > These two advantages will always be effective whether the vcpus > is more than host's cores or not. I would say that the advantage is effective as far as at least one vcpu thread executing guest I/O runs simultaneously with the back-end I/O thread (each thread on a different core). > But why the advantage of dataplane > is only so obvious when vcpus is more than host's cores? Maybe the issue is related to the fact that no-dataplane experiences more bottlenecks when your run more and more VCPU threads. So it not that dataplane performs better with more VCPUs, the issue is that no-dataplane performs worse with more VCPUs.