[Kimchi-devel] CPU discussion (RE: psutil.NUM_CPUS)

After my confusion on Paulo's patch a few weeks ago, I thought I had just gotten confused, and so I put psutil.NUM_CPUS in my SMT/HT patch. However, testing now on x86, I'm noticing a difference in the way Power and x86 report CPUS. On my laptop: <cpu> <arch>x86_64</arch> <model>SandyBridge</model> <vendor>Intel</vendor> <topology sockets='1' cores='2' threads='2'/> psutil.NUM_CPUS returns 4 On a Power7 system with 16 cores, 4 threads/core (so 64 total threads), psutil.NUM_CPUS returns 16. And this is, it turns out, because (and this sounds odd) for *guests* to be able to do SMT on Power, SMT has to be disabled. So, psutil.NUM_CPUS will not report the number of vCPUs that are available to guests. The same change would happen on x86 if you disabled HT, I assume. So, revisiting this difference that I noticed but wasn't able to articulate very well last time, do we want to make a change to the host code to use ppc64_cpu if the arch is Power, instead of psutil.NUM_CPUS? SMT *is* off, so, technically this isn't correct, but I think we should provide this information with guests in mind since we are a virtualization platform. Regards, - Christy