Managing execution of mixed workloads in a simultaneous multi-threaded (SMT) enabled system

A simultaneous multi-thread (SMT) enabled processing system, comprising:

• a plurality of processors each enabled for simultaneous execution of multiple hardware threads;
• a memory for storing a kernel for controlling application of workloads to said plurality of processors;
• said kernel operative to facilitate construction of an exclusive set of processors from among said plurality of processors to handle a plurality of tasks of an single-threaded (ST) workload;
• said kernel operative to set a separate dispatcher for each hardware thread of said exclusive set of processors to only execute work on each local run queue associated with each said hardware thread of said exclusive set of processors;
• said kernel operative to drain any waiting tasks from each local run queue associated with each said hardware thread of said exclusive set of processors;
• said kernel, responsive to placing each said hardware thread of said exclusive set of processors in an idle mode without any tasks to perform, operative to set each said hardware thread of said exclusive set of processors in a snooze mode, wherein only an interrupt awakens each said hardware thread placed in snooze mode to search an associated local run queue for waiting tasks;
• said kernel operative to schedule said ST workload on said exclusive set of processors by selecting only one hardware thread per processor within said exclusive set of processors to handle a separate one of said plurality of tasks of the ST workload while requiring the remaining hardware threads per processor within said exclusive set of processors to remain in said snooze mode, such that said ST workload is executed on a multi-threaded processor system enabled for simultaneous execution as if said exclusive set of processors are running in ST mode without removing the remaining hardware threads per processor remaining in said snooze mode within said exclusive set of processors;
• said kernel operative to apply each separate task of said ST workload to a separate local run queue of each said selected one hardware thread per processor within said exclusive set of processors;
• and
• said kernel operative to send said interrupt to wake up said selected one hardware thread per processor.

A computer program product for managing a simultaneous multi-threaded (SMT) enabled processor system comprising a plurality of processors each activated to simultaneously execute a plurality of hardware threads, said computer program product comprising:

• one or more computer-readable tangible storage devices;
• program instructions, stored on at least one of the one or more computer-readable tangible storage devices, to control construction of an exclusive set of processors from among said plurality of processors to handle a plurality of tasks of an single-threaded (ST) workload in said SMT enabled processing system;
• program instructions, stored on at least one of the one or more computer-readable tangible storage devices, to set a separate dispatcher for each hardware thread of said exclusive set of processors to only execute work on each local run queue associated with each said hardware thread of said exclusive set of processors;
• program instructions, stored on at least one of the one or more computer-readable tangible storage devices, to drain any waiting tasks from each local run queue associated with each said hardware thread of said exclusive set of processors;
• program instructions, stored on at least one of the one or more computer-readable tangible storage devices, responsive to placing each said hardware thread of said exclusive set of processors in an idle mode without any tasks to perform, to set each said hardware thread of said exclusive set of processors in a snooze mode, wherein only an interrupt awakens each said hardware thread placed in snooze mode to search an associated local run queue for waiting tasks;
• program instructions, stored on at least one of the one or more computer-readable tangible storage devices, to control scheduling of said ST workload on said exclusive set of processors by selecting only one hardware thread per processor within said exclusive set of processors to handle a separate one of said plurality of tasks of the ST workload while requiring the remaining hardware threads per processor within said exclusive set of processors to remain in said snooze mode, wherein said ST workload is executed on an SMT enabled processor system as if said exclusive set of processors are running in ST mode without removing the remaining hardware threads per processor remaining in said snooze mode within said exclusive set of processors;
• program instructions, stored on at least one of the one or more computer-readable tangible storage devices, to apply each separate task of said ST workload to a separate local run queue of each said selected one hardware thread per processor within said exclusive set of processors;
• and
• program instructions, stored on at least one of the one or more storage devices, to send said interrupt to wake up said selected one hardware thread per processor.