To schedule a software thread for execution on a CPU in a multiprocessor system, a scheduler uses both software and hardware utilization information. For a thread, resource demands (including software and hardware resource demands) are determined based on measuring resource usage while the thread executes on the multiprocessor system without being isolated from any other threads that may run concurrently. For at least two processor cores, resource usage is calculated based on any threads already running on it. The software thread is assigned to a strand in the processor core with optimum available resources given the thread's resource demands.