Method and apparatus for reducing power consumption in a computer network without sacrificing performance

A computer system comprising:

• a processor module, including means for executing a power down sequence and for executing a wake-up sequence;
• an input/output (I/O) interface module coupled to a network connection means for receiving network packets and detecting asynchronous events initiated by sources external to the computer system;
• a main memory for storing data including state information of the processor module;
• and
• a system controller coupled to the I/O interface module and the processor module;
• the power down sequence including storing data including state information of the processor module in the main memory and powering down the processor module while the I/O interface module remains powered up;
• the I/O interface module including means for responding to detection of the asynchronous event by sending an interrupt request to the system controller, and for regenerating the interrupt request until a positive acknowledgment of the interrupt request is received;
• the system controller including means for responding to a first interrupt request corresponding to the asynchronous event by causing the processor module to power up and start executing the wake-up sequence, and for responding to each interrupt request corresponding to the asynchronous event by (A) sending the I/O interface module a negative acknowledgment of the interrupt request if the processor module has not completed the wake-up sequence, and (B) generating a positive acknowledgement of the interrupt request and sending to the processor module an interrupt packet corresponding to the asynchronous event if the processor module has completed the wake-up sequence.

A method for managing power in a computer network having a plurality of computer systems and a network connection means, each said computer system including a processor module, an input/output (I/O) interface module and a main memory, each I/O interface module coupled to the network connection means, the method comprising the steps of:

• performing a powering down sequence in a first one of the computer systems to transition the first computer system from an awake state into a sleep state, including:
• storing data including state information of the first processor module in a first said main memory of the first computer system;
• and
• powering down the first processor module while a first said I/O interface module of the first computer system remains powered up, thereby reducing the power consumption of the computer network;
• detecting an asynchronous event initiated by a source external to the first computer system;
• and
• responding to the detection of the asynchronous event by:
• powering up the first processor module and performing a wake-up sequence in the first processor module;
• generating, within the first computer system, an internal interrupt request corresponding to the asynchronous event and regenerating the interrupt request whenever a negative acknowledgment of the interrupt request is generated;
• and
• responding to each interrupt request corresponding to the asynchronous event by (A) generating a negative acknowledgment of the interrupt request if the first processor module has not completed the wake-up sequence, and (B) generating a positive acknowledgment of the interrupt request and sending to the first processor module an interrupt packet corresponding to the asynchronous event if the first processor module has completed the wake-up sequence.

A computer system comprising:

• a processor module, including means for executing a power down sequence and for executing a wake-up sequence;
• an input/output (I/O) interface module coupled to a network connection means for receiving network packets and detecting asynchronous events initiated by sources external to the computer system;
• a main memory for storing data including state information of the processor module;
• and
• a system controller coupled to the I/O interface module and the processor module;
• the power down sequence including storing data including state information of the processor module in the main memory and powering down the processor module while the I/O interface module remains powered up;
• the I/O interface module including means for responding to detection of an asynchronous event by sending an interrupt request to the system controller, and for regenerating the interrupt request whenever a negative acknowledgment of the interrupt request is received;
• the system controller including means for responding to a first interrupt request corresponding to the asynchronous event by causing the processor module to power up and start executing the wake-up sequence, and for responding to each interrupt request corresponding to the asynchronous event by (A) sending the I/O interface module a negative acknowledgment of the interrupt request if the processor module has not completed the wake-up sequence, and (B) generating a positive acknowledgment of the interrupt request and sending to the processor module an interrupt packet corresponding to the asynchronous event if the processor module has completed the wake-up sequence.