orterun (the Open MPI SPMD/MPMD launcher; mpirun/mpiexec are just symlinks to it) has some support for process binding but it is not flexible enough to allow you to bind two processes per core. You can try with -bycore -bind-to-core but it will err when all cores already have one process assigned to them. But there … Read more
See my answer on a softwareengineering.SE question for some details about how modern CPUs find and exploit instruction-level parallelism (ILP) by running multiple instructions at once. (Including a block diagram of Intel Haswell’s pipeline, and links to more CPU microarchitecture details). Also Modern Microprocessors A 90-Minute Guide! You have a CPU with lots of execution … Read more
Multi-CPU was the first version: You’d have one or more mainboards with one or more CPU chips on them. The main problem here was that the CPUs would have to expose some of their internal data to the other CPU so they wouldn’t get in their way. The next step was hyper-threading. One chip on … Read more
EDIT: This is no longer 100% correct due to Intel’s ongoing befuddlement. The way I understand the question is that you are asking how to detect the number of CPU cores vs. CPU threads which is different from detecting the number of logical and physical cores in a system. CPU cores are often not considered … Read more