[$] Fixing a corner case in asymmetric CPU packing

Linux supports processor architectures where CPUs in the same systemmight have different processing capacities; for example, the Arm big.LITTLEsystems combine fast, power-hungry CPUs with slower, more efficientones. Linux has also run for years on simultaneousmultithreading (SMT) architectures, where one CPU executes multipleindependent execution threads and is seen as if it were multiple cores.There are architectures that mix both approaches. A recent discussionon a patchset submitted by Ricardo Neri shows that, on these systems, thescheduler might distribute tasks in an inefficient way.