System for dynamically managing power consumption in a search engine
View Patent ↗The power consumption of a search engine such as a CAM device is dynamically adjusted to prevent performance degradation and/or damage resulting from overheating. For some embodiments, the CAM device is continuously sampled to generate sampling signals indicating the number of active states and number of compare operations performed during each sampling period. The sampling signals are accumulated to generate an estimated device power profile, which is compared with reference values corresponding to predetermined power levels to generate a dynamic power control signal indicating predicted increases in the device's operating temperature resulting from its power consumption. The dynamic power control signal is then used to selectively reduce the input data rate of the CAM device, thereby reducing power consumption and allowing the device to cool.
1. A search system including a content addressable memory (CAM) device, comprising:
a CAM array having a plurality of rows, each row including a number of CAM cells coupled to a match latch, the match latch to store match signals generated during compare operations;
a sampling circuit, coupled to the CAM array, to generate sampling signals indicating how many of the match signals are asserted during a sampling period; and
a throttle control circuit to selectively adjust an input data rate at which an input string is provided to the CAM array in response to the sampling signals.
2. The search system of claim 1 , wherein the sampling signals indicate power consumption of the CAM array.
3. The search system of claim 1 , further comprising:
an accumulator circuit to generate an estimated power profile signal in response to the sampling signals, wherein the estimated power profile signal indicates a time-averaged power profile of the CAM array.
4. The search system of claim 3 , wherein the accumulator circuit is to logically combine the sampling signals during the sampling period to generate the estimated power profile signal.
5. The search system of claim 3 , further comprising:
a compare circuit to compare the estimated power profile signal with one or more reference values to generate a dynamic power control signal.
6. The search system of claim 5 , wherein the compare circuit comprises:
a look-up table having an input to receive the estimated power profile signal and having a plurality of locations for storing a plurality of different reference values; and
a memory element coupled to the look-up table and having a plurality of locations for storing a plurality of different values of the dynamic power control signal.
7. The search system of claim 5 , wherein the throttle control circuit is to decrease the input data rate if the dynamic power control signal exceeds a reference value.
8. The search system of claim 7 , wherein the throttle control circuit is to decrease the input data rate until the dynamic power control signal falls below the reference value.
9. The search system of claim 7 , wherein the throttle control circuit is to increase the input data rate after the dynamic power control signal falls below the reference value.
10. The search system of claim 7 , wherein the reference value corresponds to a predicted temperature increase of the CAM device resulting from power consumption.
11. A search system for dynamically adjusting power consumption of a content addressable memory (CAM) device, the system comprising:
means for generating match signals during compare operations performed in the CAM device;
means for sampling the match signals to generate sampling signals indicating how many of the match signals are asserted during a sampling period; and
means for generating an estimated power profile signal in response to the sampling signals, wherein the estimated power profile signal indicates a time-averaged power profile of the CAM device.
12. The system of claim 11 , further comprising:
means for selectively adjusting an input data rate at which an input string is provided to the CAM device in response to the estimated power profile signal.
13. The system of claim 12 , wherein the means for selectively adjusting the input data rate comprises:
means for comparing the estimated power profile signal to a reference value; and
means for decreasing the input data rate when the estimated power profile signal exceeds the reference value.
14. The system of claim 13 , further comprising:
means for increasing the input data rate when the dynamic power control signal falls below the reference value.
15. The system of claim 13 , wherein the reference value corresponds to a predicted increase in operating temperature resulting from power consumption of the CAM device.
16. The system of claim 12 , wherein selectively adjusting the input data comprises:
means for comparing the estimated power profile signal to a number of reference values;
means for selecting a corresponding one of a number of power control signals in response to the comparing; and
means for selectively decreasing the input data rate in response to the selected power control signal.
17. The system of claim 11 , wherein the number of match signals asserted during the sampling period is indicative of the power consumption of the CAM device.
18. The system of claim 11 , wherein the sampling signals further indicate the number of compare operations performed during the sampling period.
19. The system of claim 11 , wherein the estimated power profile signal (EPP) is expressed as EPP=(S*C)/T, where S is the number of match signals asserted during the sampling period, C is the number of compare operations performed during the sampling period, and T is the time duration of the sampling period.
20. The system of claim 11 , wherein the sampling signals further indicate the number of clock signals elapsed during the sampling period.