Method and apparatus for reducing power consumption in a computer system by placing the CPU in a low power mode
DCFirst Claim
1. A computer system with power management comprising:
- a central processing unit, said central processing unit having an active mode wherein it is responsive to external events, and a standby mode wherein power is maintained to said central processing unit and said central processing unit is in a low power state and is not responsive to said external events, said central processing unit operative such that whenever said central processing unit has completed a series of basic housekeeping functions and a next operation to be performed by said central processing unit is a no operation idle step, said central processing unit sets a condition indicating that said central processing unit is currently not required; and
a power management circuit coupled to said central processing unit, said power management circuit being operative to monitor for said external events when said central processing unit is in said standby mode, and to cause said central processing unit to enter said active mode upon the detection of an external event, said power management circuit being operative to force said central processing unit into said standby mode in response to the condition indicating that said central processing unit is currently not required.
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Abstract
A computer system including a central processing unit (CPU) and a power management circuit (PMC). The CPU has an active mode where it is responsive to interrupt and direct memory access requests, and a standby mode where it is in a low power state and is not responsive to the interrupts and direct memory access requests. The PMC monitors the interrupts and direct memory access requests in the system when the CPU is in the standby mode, and causes the CPU to enter the active mode upon the detection of either an interrupt or a direct memory access request. The PMC includes: a standby register having a content which indicates either a standby or an active mode for the CPU; logic coupled to the standby register to produce a standby enabling output signal when the content of the standby register indicates a standby mode, and to produce a standby disabling output signal when the content of the standby register indicates an active mode; and logic which forces the content of the standby register to the active mode upon the detection of either an interrupt or a direct memory access request. A method for managing power consumed by a CPU of a computer system includes forcing the CPU to enter a low-power standby mode, monitoring the computer system for interrupts and direct memory access requests, and reactivating the central processing unit to an active mode where the CPU is capable of responding to the detected requests.
47 Citations
20 Claims
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1. A computer system with power management comprising:
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a central processing unit, said central processing unit having an active mode wherein it is responsive to external events, and a standby mode wherein power is maintained to said central processing unit and said central processing unit is in a low power state and is not responsive to said external events, said central processing unit operative such that whenever said central processing unit has completed a series of basic housekeeping functions and a next operation to be performed by said central processing unit is a no operation idle step, said central processing unit sets a condition indicating that said central processing unit is currently not required; and a power management circuit coupled to said central processing unit, said power management circuit being operative to monitor for said external events when said central processing unit is in said standby mode, and to cause said central processing unit to enter said active mode upon the detection of an external event, said power management circuit being operative to force said central processing unit into said standby mode in response to the condition indicating that said central processing unit is currently not required. - View Dependent Claims (2, 3, 4, 5, 6, 7, 8, 9, 10)
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11. A method for managing power consumed by a computer system comprising the steps of:
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forcing a central processing unit of a computer system to enter a low-power standby mode when said central processing unit has completed a series of basic housekeeping functions and a next operation to be performed by said central processing unit is a no operation idle step; monitoring said computer system for external events to which said central processing unit should respond; and reactivating said central processing unit to an active mode where said central processing unit is capable of responding to said external events. - View Dependent Claims (12, 13, 14, 15, 16, 17)
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18. A method for managing power consumed by a computer system having a central processing unit, a power management device, and a peripheral device, wherein said power management device controls power to said peripheral device, the method comprising the steps of:
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implementing a process on said computer system, said process having an executable instruction set for transferring data to said peripheral device; and patching said process to modify a functionality of said process such that the execution of said executable instruction set for writing data to said peripheral device includes instructing said power management device to enable power to said peripheral device prior to transferring data to said peripheral device, transferring data to said peripheral device once said peripheral device has power, and then instructing said power management circuit to disable power to said peripheral device after the data transfer is complete. - View Dependent Claims (19, 20)
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Specification