System and method for dynamically adjusting to CPU performance changes

A computer system, comprising:

• memory;
• a processor connected to the memory, wherein the processor includes a performance control input and wherein the processor is capable of operating at a plurality of performance states, including a first and a second performance state;
• performance control logic connected to the performance control input of the processor, wherein the performance control logic shifts the processor between the first and second performance states as a function of a signal applied to said performance control input;
• and
• a notification mechanism for notifying processes that use real-time threads so that the processes can adjust to performance state changes, wherein the notification mechanism includes means for measuring CPU performance at the second performance state and means for communicating the measured CPU performance to processes that use real-time threads.

A computer system, comprising:

• memory;
• a processor connected to the memory, wherein the processor includes a power input and a clock input and wherein the processor is capable of operating at a plurality of performance states, including a first and a second performance state;
• performance control logic connected to the clock input of the processor, wherein the performance control logic shifts the processor between the first and second performance states as a function of a signal transmitted to said clock input;
• and
• a notification mechanism for notifying processes that use real-time threads so that the processes can adjust to performance state changes, wherein the notification mechanism includes means for measuring CPU performance at the second performance state and means for communicating the measured CPU performance to processes that use real-time threads.

A computer-readable medium for use in a computer system having a processor capable of operating at a plurality of performance states, including a first and a second performance state, comprising:

• program code for switching between the first and second performance states;
• program code for halting task scheduling;
• program code for measuring CPU performance at the second performance state;
• program code for resuming task scheduling;
• and
• program code for adjusting tasks as a function of CPU performance at the second performance state, wherein the program code for adjusting tasks includes program code for notifying each task executing real-time threads of the transition between performance states and program code for modifying execution of the tasks executing real-time threads to correct for performance state dependencies in execution of the tasks by a processor operating at the second performance state.

An operating system, comprising:

• a scheduler, wherein the scheduler schedules threads;
• a performance state transition controller, wherein the performance state transition controller controls changes between performance states;
• and
• a notification mechanism for notifying processes that use real-time threads so that the processes can adjust to performance state changes, wherein the notification mechanism includes means for measuring CPU performance at the second performance state and means for communicating the measured CPU performance to processes that use real-time threads.