On Dec 11, 2014, at 1:36 PM, Brock Palen <bro...@umich.edu> wrote: > Ok let me expand then. I don't have control over the bios. > > The testing I am doing resides on a cloud provider and from our testing it > appears that it has HT enabled. It is ambiguous though to me what I see vs > how they allocate on their hypervisor.
Oh, if you're in a hypervisor, then what you're seeing has zero correlation to reality. If it's an HPC cloud provider, they *likely* paired cores in the hypervisor with real/physical cores. More specifically: they *probably* paired hyper threads in the hypervisor with real/physical hyper threads (i.e., so that the lstopo in the hypervisor is equivalent to lstopo outside the hypervisor). But you'll need to ask them, because modern VMs let you do whatever you want in terms of mapping VM cores/HTs to physical cores/HTs. Consider: you can run dozens on web server VMs on a machine with 10 cores. Each VM will say that it has, say, 1 or 2 cores. But clearly, the sum of number of cores in the VMs is larger than the total number of physical cores. -- Jeff Squyres jsquy...@cisco.com For corporate legal information go to: http://www.cisco.com/web/about/doing_business/legal/cri/
