Right and that is what I figured, they quote performance metrics. I'm almost trying to divine what mapping they use and if its static, 1:1 mapping.
Thanks for the thoughts. Brock Palen www.umich.edu/~brockp CAEN Advanced Computing XSEDE Campus Champion bro...@umich.edu (734)936-1985 > On Dec 11, 2014, at 4:41 PM, Jeff Squyres (jsquyres) <jsquy...@cisco.com> > wrote: > > 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/ > > _______________________________________________ > hwloc-users mailing list > hwloc-us...@open-mpi.org > Subscription: http://www.open-mpi.org/mailman/listinfo.cgi/hwloc-users > Link to this post: > http://www.open-mpi.org/community/lists/hwloc-users/2014/12/1129.php
