GRAPHICS PROCESSOR CLOCK SCALING BASED ON IDLE TIME

• US 20130179711A1
• Filed: 12/12/2012
• Published: 07/11/2013
• Est. Priority Date: 01/11/2012
• Status: Active Grant

• Current Assignee: NVIDIA Corporation
• Original Assignee: NVIDIA Corporation
• Inventors: Aelion, Ilan, Bergstrom, Terje, Longnecker, Matthew R.
• Granted Patent: US 9,773,344 B2
• Time in Patent Office: Days
• US Class Current: 713/322
• CPC Class Codes: G06F 1/3218 of display devices
• CPC Class Codes: G06F 1/324 by lowering clock frequency
• CPC Class Codes: G06F 1/3265 Power saving in display device
• CPC Class Codes: G06F 11/3423 where the assessed time is active or idle time
• CPC Class Codes: G06T 15/80 Shading
• CPC Class Codes: Y02D 10/00 Energy efficient computing, e.g. low power processors, power management or thermal management

Abstract

A method for graphics processor clock scaling comprises the following steps. A percentage of idle-time is calculated, based upon an elapsed idle-time and an elapsed active time. A graphics processor clock rate is reduced if the percentage of idle time is higher than a high limit threshold. The graphics processor clock rate is increased if the percentage of idle time is lower than a low limit threshold.

Claims

1. A method for graphics processor clock scaling, the method comprising:

calculating a percentage of idle-time based upon an elapsed idle-time of the graphics processor and an elapsed active time of the graphics processor;

reducing a graphics processor clock rate if the percentage of idle time is higher than a high limit threshold; and

increasing the graphics processor clock rate if the percentage of idle time is lower than a low limit threshold.

2. The method of claim 1, wherein the increasing comprises increasing the graphics processor clock rate a predetermined amount if the percentage of idle time is lower than a low limit threshold, and wherein the reducing comprises decreasing the graphics processor clock rate a predetermined amount if the percentage of idle time is higher than a high limit threshold.

3. The method of claim 1, wherein the low limit threshold and the high limit threshold are each adjusted based upon a proportion of graphics processor clock rate increases to graphics processor clock rate decreases.

4. The method of claim 3 further comprising:

increasing the high limit threshold and the low limit threshold when the proportion of graphics processor clock rate increases to graphics processor clock rate decreases is at a high limit; and

decreasing the high limit threshold and the low limit threshold when the proportion of graphics processor clock rate increases to graphics processor clock rate decreases is at a low limit.

5. The method of claim 1, wherein the high limit threshold is greater than 50%.

6. The method of claim 1, wherein the low limit threshold is less than 50%.

7. The method of claim 4, wherein the proportion high limit is 4:

1 and the proportion low limit is 1;

1.

8. A method for graphics processor clock scaling, the method comprising:

counting a quantity of clock scale-up decisions and a quantity of clock scale-down decisions over a first evaluation period of a plurality of scale-up evaluation periods and a plurality of scale-down evaluation periods, wherein the clock scale-up decisions and the clock scale-down decisions increase and decrease a graphics processor clock rate, respectively, when a percentage of idle time in a scale-up evaluation period is lower than a selected idle-time percentage low-limit value and when a percentage of idle time in a scale-down evaluation period is higher than a selected idle-time percentage high-limit value, respectively;

calculating a proportion of clock scale-up decisions to clock scale-down decisions; and

increasing the idle-time percentage high-limit value and the idle-time percentage low-limit value if the proportion of clock scale-up decisions to clock scale-down decisions is at a high limit and decreasing the idle-time percentage high-limit value and the idle-time percentage low-limit value if the proportion of clock scale-up decisions to clock scale-down decisions is at a low limit.

9. The method of claim 8 further comprising:

increasing the graphics processor clock rate a predetermined amount if the percentage of idle time is lower than the selected idle-time percentage low-limit value; and

decreasing the graphics processor clock rate a predetermined amount if the percentage of idle time is higher than the selected idle-time percentage high-limit value.

10. The method of claim 8, wherein the selected idle-time percentage high-limit value is greater than 50%, and wherein the selected idle-time percentage low-limit value is less than 50%.

11. The method of claim 8, wherein the proportion high limit is 4:

1 and the proportion low limit is 1;

1.

12. The method of claim 8, wherein increasing the idle-time percentage high-limit value and increasing the idle-time percentage low-limit value increases the idle-time percentage high-limit value and the idle-time percentage low-limit value by a maximum of 50%.

13. The method of claim 8, wherein decreasing the idle-time percentage high-limit value and decreasing the idle-time percentage low-limit value decreases the idle-time percentage high-limit value and the idle-time percentage low-limit value by a maximum of 50%.

14. A computer system comprising:

a processor;

a graphics processor;

a memory; and

a clock generator, wherein the clock generator is operable to generate clock signals for the processor and the graphics processor, wherein the memory is operable to store instructions, that when executed by the processor perform a method of scaling a clock output of the clock generator to the graphics processor, the method comprising;

calculating a percentage of idle-time based upon an elapsed idle-time and an elapsed active time;

reducing a graphics processor clock rate if the percentage of idle time is higher than a high limit threshold; and

increasing the graphics processor clock rate if the percentage of idle time is lower than a low limit threshold.

15. The computer system of claim 14, wherein the method further comprises:

increasing the graphics processor clock rate a predetermined amount if the percentage of idle time is lower than a low limit threshold; and

decreasing the graphics processor clock rate a predetermined amount if the percentage of idle time is higher than a high limit threshold.

16. The computer system of claim 14, wherein the method further comprises adjusting the low limit threshold and the high limit threshold based upon a proportion of graphics processor clock rate increases to graphics processor clock rate decreases.

17. The computer system of claim 16, wherein the high limit threshold and the low limit threshold are increased when the proportion of graphics processor clock rate increases to graphics processor clock rate decreases is at a high limit, and wherein the high limit threshold and the low limit threshold are decreased when the proportion of graphics processor clock rate increases to graphics processor clock rate decreases is at a low limit.

18. The computer system of claim 14, wherein the high limit threshold is greater than 50%.

19. The computer system of claim 14, wherein the low limit threshold is less than 50%.

20. The computer system of claim 17, wherein the proportion high limit is 4:

1 and the proportion low limit is 1;

1.