Power Management in a Multi-Processor Computer System

A system for dispatching a task in a computer system, the system comprising:

• a computer memory;
• and
• a processor in communication with the computer memory, the processor comprising an instruction fetching element for fetching instructions from memory and one or more execution elements for executing fetched instructions;
• wherein the computer system is configured to perform a method comprising:
• receiving a task for execution in a high power state;
• determining a current power state of a processor, the processor one of a plurality of processors in a multi-processor system, the multi-processor system having a specified power limit;
• dispatching the task to the processor in response to determining that the current power state of the processor is the high power state;
• and
• in response to determining that the current power state of the processor is not the high power state:
• determining if moving the processor into the high power state will cause the multi-processor system to exceed the specified power limit, the determining responsive to the specified power limit and to current power states of the plurality of processors in the multi-processor system;
• moving the processor into the high power state in response to determining that moving the processor into the high power state will not cause the multi-processor system to exceed the specified power limit;
• and
• dispatching the task to the processor in response to the moving the processor into the high power state.

A computer implemented method for dispatching a task in a computer system, the method comprising:

• receiving a task for execution in a high power state;
• determining a current power state of a processor, the processor one of a plurality of processors in a multi-processor system, the multi-processor system having a specified power limit;
• dispatching the task to the processor in response to determining that the current power state of the processor is the high power state;
• and
• in response to determining that the current power state of the processor is not the high power state:
• determining if moving the processor into the high power state will cause the multi-processor system to exceed the specified power limit, the determining responsive to the specified power limit and to current power states of each of the plurality of processors in the multi-processor system;
• moving the processor into the high power state in response to determining that moving the processor into the high power state will not cause the multi-processor system to exceed the specified power limit;
• and
• dispatching the task to the processor in response to the moving the processor into the high power state.

A computer program product for dispatching a task in a computer system, the computer program product comprising:

• a tangible storage medium readable by a processing circuit and storing instructions for execution by the processing circuit for performing a method comprising:
• receiving a task for execution in a low power state;
• determining a current power state of a processor, the processor one of a plurality of processors in a multi-processor system, the multi-processor system having a specified power limit;
• dispatching the task to the processor in response to determining that the current power state of the processor is the low power state;
• and
• in response to determining that the current power state of the processor is not the low power state:
• moving the processor into the low power state;
• and
• dispatching the task to the processor in response to the moving the processor into the low power state.