Demand-based method and system of CPU power management

Abstract

A demand-based method and system of central processing unit power management. The utilization of a central processing unit (CPU) during a sampling time interval is determined by measuring a time quantum within the sampling time interval during which a central processing unit clock signal is active within a processor core of the CPU. The total number of cycles of the central processing unit clock signal that are applied to the processor core and the period of the central processing unit clock signal are used to determine the time quantum. The utilization may then be expressed in terms of a ratio of the time quantum to the total time interval and used to select a processor performance mode. The CPU is then operated in the selected processor performance mode.

1 . A method comprising: 
 determining a utilization of a central processing unit;    placing said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than a first utilization threshold;    placing said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to said first utilization threshold, wherein said central processing unit operates at a higher frequency in said first processor performance mode than in said second processor performance mode.    
   
   
       2 . The method as set forth in  claim 1 , further comprising: 
 placing said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to a second utilization threshold, wherein said second utilization threshold is greater than said first utilization threshold and said central processing unit operates at a higher frequency in said third processor performance mode than in said second processor performance mode.    
   
   
       3 . The method as set forth in  claim 1 , wherein placing said central processing unit in a first processor performance mode comprises: 
 receiving a user-specified power management profile; and    placing said central processing unit in said first processor performance mode in response to receiving said user-specified power management profile.    
   
   
       4 . The method as set forth in  claim 1 , wherein placing said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than a first utilization threshold comprises placing said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than 20%.  
   
   
       5 . The method as set forth in  claim 4 , wherein placing said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to said first utilization threshold comprises placing said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to 20%.  
   
   
       6 . The method as set forth in  claim 2 , wherein placing said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to a second utilization threshold comprises placing said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to 20%.  
   
   
       7 . A data processing system-readable medium having a plurality of instructions executable by a data processing system embodied therein, wherein said instructions when executed cause said data processing system to perform a method comprising: 
 determining a utilization of a central processing unit;    placing said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than a first utilization threshold;    placing said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to said first utilization threshold, wherein said central processing unit operates at a higher frequency in said first processor performance mode than in said second processor performance mode.    
   
   
       8 . The data processing system-readable medium as set forth in  claim 7 , wherein said method further comprises: 
 placing said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to a second utilization threshold, wherein said second utilization threshold is greater than said first utilization threshold and said central processing unit operates at a higher frequency in said third processor performance mode than in said second processor performance mode.    
   
   
       9 . The data processing system-readable medium as set forth in  claim 7 , wherein placing said central processing unit in a first processor performance mode comprises: 
 receiving a user-specified power management profile; and    placing said central processing unit in said first processor performance mode in response to receiving said user-specified power management profile.    
   
   
       10 . The data processing system-readable medium as set forth in  claim 7 , wherein placing said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than a first utilization threshold comprises placing said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than 20%.  
   
   
       11 . The data processing system-readable medium as set forth in  claim 10 , wherein placing said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to said first utilization threshold comprises placing said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to 20%.  
   
   
       12 . The data processing system-readable medium as set forth in  claim 8 , wherein placing said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to a second utilization threshold comprises placing said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to 95%.  
   
   
       13 . A plurality of instructions executable by a data processing system and embodied within a data processing system-readable medium, comprising: 
 a first code segment to determine a utilization of a central processing unit;    a second code segment to place said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than a first utilization threshold;    a third code segment to place said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to said first utilization threshold, wherein said central processing unit operates at a higher frequency in said first processor performance mode than in said second processor performance mode.    
   
   
       14 . The plurality of instructions as set forth in  claim 13 , wherein said second code segment to place said central processing unit in a first processor performance mode comprises: 
 a fourth code segment to receive a user-specified power management profile; and    a fifth code segment to place said central processing unit in said first processor performance mode in response to receiving said user-specified power management profile.    
   
   
       15 . The plurality of instructions as set forth in  claim 13 , further comprising: 
 a sixth code segment to place said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to a second utilization threshold, wherein said second utilization threshold is greater than said first utilization threshold and said central processing unit operates at a higher frequency in said third processor performance mode than in said second processor performance mode.    
   
   
       16 . The plurality of instructions as set forth in  claim 13 , wherein said second code segment to place said central processing unit in a first processor performance mode in response to a determination that said utilization is greater than a first utilization threshold comprises a code segment to place said central processing unit in said first processor performance mode in response to a determination that said utilization is greater than 20%.  
   
   
       17 . The plurality of instructions as set forth in  claim 16 , wherein said third code segment to place said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to said first utilization threshold comprises a code segment to place said central processing unit in a second processor performance mode in response to a determination that said utilization is less than or equal to 20%.  
   
   
       18 . The plurality of instructions as set forth in  claim 15 , wherein said sixth code segment to place said central processing unit in a third processor performance mode in response to a determination that said utilization is greater than or equal to a second utilization threshold comprises a code segment to place said central processing unit in said third processor performance mode in response to a determination that said utilization is greater than or equal to 20%.