1. A system comprising non-transitory tangible computer-readable storage media encoded with operating-system code configured to, when executed by a multi-threaded multi-core processor: recognize and schedule processes for execution on each of plural hardware threads of said processor; and represent said processor to a client application as having multiple cores with a single hardware thread per core only while an attribute for said client application is not set, said operating-system code being further configured to, when said attribute is set, represent each of said hardware threads to said client application.