Controlling performance/power by frequency control of the responding node

Abstract

A processing node tracks probe activity level associated with its internal caching or memory system. If the probe activity level increases above a threshold probe activity level, the performance state of the processing node is increased above its current performance state to provide enhanced performance capability in responding to the probe requests. After entering the higher performance state in response to the probe activity level being above the threshold probe activity level, the processing nodes returns to a lower performance state in response to a reduction in probe activity. There may be multiple threshold probe activity levels and associated performance states.

1 . A method comprising:
 tracking probe activity level in a processing node; and   comparing the probe activity level to a first threshold probe activity level.   
     
     
         2 . The method as recited in  claim 1  further comprising:
 increasing a performance state of the processing node to a first performance state higher than a current performance state if the probe activity level is above the first threshold probe activity level. 
 
     
     
         3 . The method as recited in  claim 2  further comprising after entering the first performance state in response to the probe activity level being above the threshold probe activity level, entering a second performance state lower than the first performance state when the probe activity level falls below a predetermined level below the first threshold probe activity. 
     
     
         4 . The method as recited in  claim 3  further comprising entering the second performance state when the probe activity level is less than the first threshold less a hysteresis factor. 
     
     
         5 . The method as recited in  claim 3  wherein the second performance state is a performance state from which the processing node entered the first performance state. 
     
     
         6 . The method as recited in  claim 3  wherein the first and second performance states are defined by at least one of voltage and frequency. 
     
     
         7 . The method as recited in  claim 2  further comprising increasing the performance state of the processing node to a third performance state in response to the probe activity level increasing above a second threshold probe activity level, the second threshold probe activity level being higher than the first threshold probe activity level, and wherein the third performance state is higher than the first performance state. 
     
     
         8 . The method as recited in  claim 7  further comprising after increasing the performance state of the processing node to the third performance state in response to the probe activity level increasing above the second threshold probe activity level, reducing the performance state. 
     
     
         9 . The method as recited in  claim 1  further comprising beginning the tracking of the probe activity level when the processing node is in a performance state lower than the first performance state. 
     
     
         10 . The method as recited in  claim 1  wherein tracking the probe activity further comprises entering each probe request into a queue and retiring a probe request from the queue after the processing node responds to the probe request with at least one of a data movement and a response. 
     
     
         11 . The method as recited in  claim 10  further comprising comparing a number of entries in the queue to the first threshold probe activity level to determine if the probe activity level is above the first threshold probe activity level. 
     
     
         12 . The method as recited in  claim 1  wherein tracking the probe activity further comprises incrementing a count value indicative of a level of probe activity in response to occurrence of probe activity and decrementing the count value based on passage of a predetermined amount of time. 
     
     
         13 . An apparatus comprising:
 a probe tracker to track probe activity level in a processing node;   wherein the apparatus is responsive to increase a performance state of the processing node from a current performance state to a first performance state if the probe activity level increases above a first threshold probe activity level.   
     
     
         14 . The apparatus as recited in  claim 13  wherein the apparatus is responsive to the probe activity level falling a predetermined level below the first threshold probe activity level to cause the processing node to enter a second performance state lower than the first performance state. 
     
     
         15 . The apparatus as recited in  claim 14  wherein the first and second performance states are defined by at least one of voltage and frequency. 
     
     
         16 . The apparatus as recited in  claim 13  wherein the apparatus is further operable to increase the performance state of the processing node to a third performance state in response to the probe activity level increasing above a second threshold probe activity level, the second threshold probe activity level being higher than the first threshold probe activity level, and wherein the third performance state is higher than the first performance state. 
     
     
         17 . The apparatus as recited in  claim 13  wherein the probe tracker is responsive to the node being in a performance state below the first performance state to begin the tracking of the probe activity level. 
     
     
         18 . The apparatus as recited in  claim 13  wherein the probe tracker further comprises a queue into which probe request is entered and from which a probe request in the queue is retired after the processing node responds to the probe request with at least one of a data movement and a response. 
     
     
         19 . The apparatus recited in  18  further wherein the apparatus is operable to compare a number of entries in the queue to the first threshold probe activity level to determine if the probe activity level is above a first threshold probe activity level. 
     
     
         20 . The apparatus as recited in  claim 13  wherein the probe tracker comprises a counter responsive to probe activity to increment a count value indicative of a level of probe activity and responsive to a passage of a predetermined period of time to decrement the count value.