Multiprocessor system controlling frequency of clock input to processor according to ratio of processing times of processors, and method thereof

• US 6,928,566 B2
• Filed: 08/14/2001
• Issued: 08/09/2005
• Est. Priority Date: 01/18/2001
• Status: Expired due to Fees

• Current Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Original Assignee: Renesas Technology Corporation (Renesas Electronics Corporation)
• Inventors: Nunomura, Yasuhiro
• Primary Examiner(s): Fleming, Fritz M.
• Application Number:
  US09/928,358
• Publication Number:
  US 20020095610A1
• Time in Patent Office: 1,456 Days
• Field of Search: 713400-601, 713321-324
• US Class Current: 713/322
• CPC Class Codes: G06F 1/3203 Power management, i.e. event-based initiation of a power-saving mode
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/329 by task scheduling
• CPC Class Codes: G06F 1/3296 by lowering the supply or operating voltage
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

The first processor controls the clock frequency control unit according to a ratio between an estimate of the processing time of the first program and an estimate of the processing time of the second program, to change the frequency of a clock being input into the first processor. In addition, the first processor controls the variable power source according to the frequency of the clock being input into the first processor, to change the power supply voltage being supplied to the first processor. Thus, the power consumption of the first processor can be reduced considerably.

Claims

1. A multiprocessor system having a plurality of processors synchronized, comprising:

a first processor for performing at least first predetermined processing;

a second processor, different from said first processor, for performing at least second predetermined processing; and

a clock frequency control unit for controlling a frequency of a clock being input to said first processor, according to a ratio between a processing time of said first processor necessary to complete said first predetermined processing and a processing time of said second processor necessary to complete said second predetermined processing.

2. The multiprocessor system according to claim 1, further comprising a voltage control unit for controlling a power supply voltage being supplied to said first processor, according to the frequency of the clock being input to said first processor.

3. The multiprocessor system according to claim 1, further comprising:

a storage unit in which an estimate of the processing time of said first processor and an estimate of the processing time of said second processor are prestored; and

a frequency changing unit for changing the frequency of the clock being input to said first processor by controlling said clock frequency control unit according to a ratio between the estimate of the processing time of said first processor and the estimate of the processing time of said second processor that are stored in said storage unit.

4. The multiprocessor system according to claim 1, further comprising:

a storage unit in which a ratio between an estimate of the processing time of said first processor and an estimate of the processing time of said second processor is prestored; and

a frequency changing unit for changing the frequency of the clock being input to said first processor by controlling said clock frequency control unit according to the ratio stored in said storage unit.

5. The multiprocessor system according to claim 1, further comprising a frequency determining unit that causes said clock frequency control unit to lower the frequency of the clock being input to said first processor when processing of said first processor was completed earlier than processing of said second processor in a previous time of processing, and that causes said clock frequency control unit to raise the frequency of the clock being input to said first processor when the processing of said second processor was completed earlier than the processing of said first processor in the previous time of processing.

6. The multiprocessor system according to claim 1, further comprising:

a predicting unit for predicting which one of processing of said first processor and processing of said second processor will be completed earlier than the other; and

a frequency changing unit for changing the frequency of the clock being input to said first processor by controlling said clock frequency control unit according to the predicted result by said predicting unit.

7. The multiprocessor system according to claim 1, further comprising:

a predicting unit for predicting that said first processor will complete processing first when processing of said first processor was completed earlier than processing of said second processor in a previous time of processing, and predicting that said second processor will complete processing first when the processing of said second processor was completed earlier than the processing of said first processor in the previous time of processing; and

a frequency changing unit for changing the frequency of the clock being input to said first processor by controlling said clock frequency control unit according to the predicted result by said predicting unit.

8. The multiprocessor system according to claim 1, further comprising:

a predicting unit for predicting that said second processor will complete processing first when processing of said first processor was completed earlier than processing of said second processor in a previous time of processing, and predicting that said first processor will complete processing first when the processing of said second processor was completed earlier than the processing of said first processor in the previous time of processing; and

a frequency changing unit for changing the frequency of the clock being input to said first processor by controlling said clock frequency control unit according to the predicted result by said predicting unit.

9. The multiprocessor system according to claim 1, further comprising:

a first counting unit for counting the processing time of said first processor;

a second counting unit for counting the processing time of said second processor; and

a frequency changing unit for changing the frequency of the clock being input to said first processor by controlling said clock frequency control unit according to the counted result by said first counting unit and the counted result by said second counting unit.

10. A control method of a multiprocessor system having a plurality of synchronized processors, comprising the steps of:

calculating a ratio between a processing time of a first processor necessary to complete first predetermined processing and a processing time of a second processor necessary to complete second predetermined processing; and

controlling a frequency of a clock being input to said first processor according to said calculated ratio.

11. The control method of the multiprocessor system according to claim 10, further comprising the step of controlling a power supply voltage being supplied to said first processor according to the frequency of the clock being input to said first processor.

12. The control method of the multiprocessor system according to claim 10, wherein said step of controlling the frequency of the clock being input to said first processor includes the steps of

calculating a ratio between a prestored estimate of the processing time of said first processor and a prestored estimate of the processing time of said second processor, and

changing the frequency of the clock being input to said first processor according to the calculated ratio.

13. The control method of the multiprocessor system according to claim 10, wherein said step of controlling the frequency of the clock being input to said first processor includes the step of changing the frequency of the clock being input to said first processor according to a prestored ratio of an estimate of the processing time of said first processor and an estimate of the processing time of said second processor.

14. The control method of the multiprocessor system according to claim 10, wherein said step of controlling the frequency of the clock being input to said first processor includes the step of lowering the frequency of the clock being input to said first processor in the case where processing of said first processor was completed earlier than processing of said second processor in a previous time of processing, and raising the frequency of the clock being input to said first processor in the case where the processing of said second processor was completed earlier than the processing of said first processor in the previous time of processing.

15. The control method of the multiprocessor system according to claim 10, wherein said step of controlling the frequency of the clock being input to said first processor includes the steps of

predicting which one of processing of said first processor and processing of said second processor will be completed earlier than the other, and

changing the frequency of the clock being input to said first processor according to the predicted result.

16. The control method of the multiprocessor system according to claim 15, wherein said step of predicting which one of the processing of said first processor and the processing of said second processor will be completed earlier than the other includes the step of predicting that the processing of said first processor will be completed first in the case where processing of said first processor was completed earlier than processing of said second processor in a previous time of processing, and predicting that the processing of said second processor will be completed first in the case where the processing of said second processor was completed earlier than the processing of said first processor in the previous time of processing.

17. The control method of the multiprocessor system according to claim 15, wherein said step of predicting which one of the processing of said first processor and the processing of said second processor will be completed earlier than the other includes the step of predicting that the processing of said second processor will be completed first in the case where processing of said first processor was completed earlier than processing of said second processor in a previous time of processing, and predicting that the processing of said first processor will be completed first in the case where the processing of said second processor was completed earlier than the processing of said first processor in the previous time of processing.

18. The control method of the multiprocessor system according to claim 10, wherein said step of controlling the frequency of the clock being input to said first processor includes the steps of

counting the processing time of said first processor,

counting the processing time of said second processor, and

changing the frequency of the clock being input to said first processor according to the counted processing time of said first processor and the counted processing time of said second processor.