Method for controlling a processor for power-saving in a computer for executing a program, compiler medium and processor system

• US 5,790,877 A
• Filed: 07/03/1996
• Issued: 08/04/1998
• Est. Priority Date: 07/06/1995
• Status: Expired due to Fees

• Current Assignee: Hitachi, Ltd.
• Original Assignee: Hitachi, Ltd.
• Inventors: Mori, Noriyasu, Takeuchi, Yooichi, Nishiyama, Hiroyasu, Nishimoto, Akira, Kikuchi, Sumio
• Primary Examiner(s): Sheikh, Ayaz R.
• Assistant Examiner(s): PHAN, RAYMOND NGAN
• Application Number:
  US08/675,033
• Time in Patent Office: 762 Days
• Field of Search: 395/750.01, 395/750.03, 395/750.04, 395/750.05, 395/750.08, 395/377, 395/381, 395/384, 395/588, 395/445, 395/452, 395/550, 395/556, 395/557, 364/707
• US Class Current: 713/323
• CPC Class Codes: G06F 1/08 Clock generators with changeable or programmable clock frequency
• CPC Class Codes: G06F 1/32 Means for saving power
• CPC Class Codes: G06F 8/4432 Reducing the energy consumption
• CPC Class Codes: G06F 9/30083 Power or thermal control instructions
• CPC Class Codes: G06F 9/3869 Implementation aspects, e.g. pipeline latches; pipeline synchronisation and clocking
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

In a processor system including a plurality of hardware resources, a method for arranging a program to suppress the power consumption by the resources includes the steps of determining which ones of the hardware resources are to be operated and from which instruction cycle to which instruction cycle to execute each instruction of the program; and based on the determination, adding an instruction to lower frequencies of clock signals inputted to the hardware resources and an instruction to restore the frequency at positions adjacent to the beginning and the end of the period during which the hardware resources are not operated and compiling the program. The processor system decodes the compiled program and lowers the frequency of the clock signal inputted to the hardware resources in accordance with the frequency lowering instruction and the frequency restoring instruction detected in the decoding step. The clock signals sent to the hardware resources are stopped by the frequency lowering instruction to the resource of the hardware resources for which the clock frequency may be lowered to zero.

Claims

1. In a processor system comprising a plurality of hardware resources, a method for arranging a program to suppress the power consumption by the hardware resources, comprising the steps of:

determining which ones of the hardware resources are to be operated and from which instruction cycle to which instruction cycle to execute each instruction of the program; and

based on the determination, adding an instruction to lower frequencies of clock signals inputted to the hardware resources and an instruction to restore the frequency at positions adjacent to the beginning and then of the period during which the hardware resources are not operated and compiling the program.

2. A method for arranging a program according to claim 1 further comprising the steps of:

decoding the compiled program; and

lowering and restoring the frequency of the clock signal inputted to the hardware resources in accordance with the frequency lowering instruction and the frequency restoring instruction detected in the decoding step.

3. A method for arranging a program according to claim 2 wherein the clock signals sent to the hardware resources are stopped by the frequency lowering instruction to the resource for which the clock frequency may be lowered to zero.

4. A method for arranging a program according to claim 3 wherein the frequency lowering instruction and the frequency restoring instruction in the compile step are OFF instruction and ON instruction designating resources in operands.

5. A method for arranging a program according to claim 1 wherein the frequency lowering instruction and the frequency restoring instruction of the compile step are frequency change instructions to designate a hardware resource and a frequency of operands.

6. A method for arranging a program according to claim 1 further comprising the steps of:

preparing a resource utilization table having the hardware resources and a series of clock cycles for providing timing signals to operate the resources arranged in two-dimensionally; and

storing the use/non-use of the respective. resources in time sequence in the determination step in the two-dimension array of the resource utilization table.

7. A processor system for suppressing power consumption in resources comprising:

a plurality of hardware resources;

means for determining which ones of the hardware resources are to be operated and from which instruction cycle to which instruction cycle to execute each instruction of a program; and

means responsive to the determination for adding an instruction to lower frequencies of clock signals inputted to the hardware resources and an instruction to restore the frequency at positions adjacent to the beginning and the end of the period during which the hardware resources are not operated and compiling the program.

8. A processor system according to claim 7 further comprising:

means for decoding the compiled program; and

means for lowering the frequency of the clock signal inputted to the hardware resources in accordance with the frequency lowering instruction and the frequency restoring instruction detected by the decoding means.

9. A processor system according to claim 8 further comprising means for stopping the clock signals sent to the hardware resources by the frequency lowering instruction to the resource of the hardware resources for which the clock frequency may be lowered to zero.

10. A processor system according to claim 9 wherein the frequency lowering instruction and the frequency restoring instruction in the compile step are OFF instruction and ON instruction designating resources in operands.

11. A processor system according to claim 7 wherein the frequency lowering instruction and the frequency restoring instruction of the compile step are frequency change instructions to designate a hardware resource and a frequency of operands.

12. A processor system according to claim 7 wherein the hardware resources includes a first register and a first arithmetic and logical operation unit used for a floating point operation and a second register and a second arithmetic and logical operation unit for a fixed point operation, the clock signals to the second register and the second arithmetic and logical operation unit are stopped during the floating point operation, and the clock signals to the first register and the first arithmetic and logical operation unit are stopped during the fixed point operation.

13. A processor system according to claim 7 wherein the hardware resources include a first cache memory used for a floating point operation, a second cache memory used for a fixed point operation, and the frequency of the clock signal to the second cache memory is lowered during the floating point operation and the frequency of the clock signal to the first cache memory is lowered during the fixed point operation.

14. A storage medium to be connected to a processor system having a plurality of hardware resources and including a code to be read and executed by the processor, comprising:

a code section representing a function to determine which ones of the hardware resources are to be operated and from which instruction cycle to which instruction cycle to execute each instruction of a program; and

a code section representing a function to add an instruction to lower frequencies of clock signals inputted to the hardware resources and an instruction to restore the frequencies at positions adjacent to the beginning and end instruction cycles of a period during which the hardware resources are not operated, based on the determination and compiling the program.

15. A storage medium according to claim 14 wherein the frequency lowering instruction and the frequency restoring instruction in the compile step are OFF instruction and ON instruction designating resources in operands.

16. A storage medium according to claim 14 wherein the frequency lowering instruction and the frequency restoring instruction of the compile step are frequency change instructions to designate a hardware resource and a frequency of operands.

17. A storage medium according to claim 14 wherein the code includes a code section for representing a function to add an instruction to designate an intermediate speed clock when a total execution time of the program is substantially shorter than a predetermined limit time.