1 EP 1 499 943 B1 2  Description FIELD OF THE INVENTION BACKGROUND OF THE INVENTION BRIEF DESCRIPTION OF THE DRAWINGS [0001] This invention generally relates to a resource allocation enhancement to the system power manage- ment mechanism. Moreparticularlythisinvention relates to shifting to high state of performance in response to a prioritized event. [0002] Designers attempt to reduce the power con- sumed by a computer system, especially, in the arena of mobile electronic devices. Mobile electronic devices in- clude battery operated computer systems such as, for example,notebook computers,subnotebookcomputers, andpersonal data assistants. By reducingthe power con- sumed by these and other battery operated devices, a user can enjoyextendeduse and operation ofthe system between battery charges. Therefore, primarily consider- ingtheadvantages to begained bybatteryoperated com- puter systems, system manufacturers have investe considerable resourcesinto researching anddeveloping technologies to aid in the reduction of power consumed by processors within these mobile electronic devices. [0003] The power consumed by a processor, such as a central processing unit (CPU), is known to be approx- imately proportionaltothe squareofthe voltage supplied to the processor times the frequency at which the proc- essor operates P ~ (V$^{2}$ x f). Given this relationship, it can be seen that reducing the frequency or the voltage will result in a reduction of the power consumed by the proc- essor. However, reducing the frequency at which the processor operatesdecreasesthe rate atwhich the proc- essor may process data. Thus, a reduction in the fre- quency at which the processor operates decreases the power consumed by the processor as well as the state of performance of the processor. [0004] Typically, CPU power management systems use an algorithm to control the performance state of the processor. The algorithm balances reducing power con- sumptionbythe processor with theprocessing demands on the processor. Generally, the algorithmcreatessome time lag or impediment prior to transiting the processor to the maximum performance state of the processor. [0005] For example, the algorithm may be grammed tospreadthe processingworkloadoftheproc- essor across three time frames rather than increase the processing rate to complete the majority of the process- ing load in one time frame and under utilize the capacity of the processor in the next two time frames. [0006] Typically, modern mobile CPU power manage- ment systems transition to higher performance states based upon a brief history of the CPU utilization. The history of CPU utilization is usually defined by a small finite window of time ending with the present. Typical mobile systems spend a significant portion of time in the [0008] The drawings refer to the invention in which: idlestate ofperformance causing eventhe mostprocess- ing intensive tasks to generally incur a delay to the max- imum performance state for a portion of a time window. Essentially, the finite window of time acts as a weighted average to impede the transition of the processor to the highest state of performance. [0007] For example,at the beginningof the processing intensive task ninety percent of the finite window of time is filled with the CPU being used at 70% of capacity due to the processor being in the idle state of performance duringthat timeframe and ten percentof the finitewindow of time is filled with the CPU being used at 100% of ca- pacity due to demand of the processing intensive task on theprocessor.Thus, the algorithmdeterminesthe av- erage percent utilization of the processor during this en- tire finite window of time to be 73% of capacity rather than its current utilization of 100% of capacity. The algo- rithm calculates ninety percent of the finite window of time multiplied by 70% utilization plus ten percent of the finite window of time multiplied by 100% utilization to equal 73% utilization. For example, an additional 40% of the window time will need to transpire to initiate a transi- tion to the next higher performance state if the trip point were set to 85%. Perhaps by the next finite window of time the % utilization of the processor will reflect its cur- rent 100% demand and the algorithm will increase the state of performance of the processor. US 5,396,635disclosesa power- conservation system in a computer system which includes a processing unit op- erating under control of an operating system. The com- puter system generates distinct call functions to the op- erating system where each call function is either in an active class or an idle class. The power conservation system has a plurality of states of operation including an ON state, a DOZE state, a SLEEP state and an OFF state. An activity monitor monitorsthe activity ofthe com- puter system and generates control signals for selecting one of the states of operation for the computer system. The activity monitor includes a storage for storing a call value for each distinct call function and activity threshold valuesfor the variousstates ofoperation. The callvalues are weighted for the call functions whereby different call functions have a greater or lesser impact on the value of an activity level. The call value for each call function is retrieved when the call function is made to the operating system. The retrieved call values are sequentially accu- mulated to form an activity value which indicates the ac- tivity level of the computer system. A comparator com- pares the activity value with the threshold values and in response to the comparison generates a control signal to a power controller which selects the states operation for the computer system, thereby regulating the power consumption of the computer system based on the ac- tivity of the computer system. 2