Method for measuring utilization of a power managed CPU
First Claim
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1. A method for computation of data processor utilization comprising the steps of:
- accumulating total data processor execution time;
accumulating data processor idle time in a power reduced state; and
initially upon an interrupt of the data processor from the power reduced state performing the steps of;
deferring interrupt service from the power reduced state to read total data processing execution time,reading data processor idle time;
accumulating data processor utilization;
totaling execution time and CPU idle time; and
thereafter upon any subsequent interrupt of the data processor from the power reduced state proceeding directly to service the interrupt.
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Abstract
An extremely low overhead method calculates CPU load in the presence of both CPU idling and frequency scaling. The method measures time the CPU is idled while waiting for a wakeup. This invention uses a feature in current DSPs with the capability of delaying ISR processing on wake from IDLE. Using this mechanism it is possible to determine the time before IDLE, the time immediately following CPU wakeup, and then run the wakeup ISR. The delta time can be accumulated and compared to total time to determine true CPU load.
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7 Claims
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1. A method for computation of data processor utilization comprising the steps of:
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accumulating total data processor execution time; accumulating data processor idle time in a power reduced state; and initially upon an interrupt of the data processor from the power reduced state performing the steps of; deferring interrupt service from the power reduced state to read total data processing execution time, reading data processor idle time; accumulating data processor utilization; totaling execution time and CPU idle time; and thereafter upon any subsequent interrupt of the data processor from the power reduced state proceeding directly to service the interrupt. - View Dependent Claims (2, 3, 4, 5, 6, 7)
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