1. Field of the Invention
The present invention relates in general to the field of information handling system power management, and more particularly to a system and method for information handling system adaptive variable bus idle timer.
2. Description of the Related Art
As the value and use of information continues to increase, individuals and businesses seek additional ways to process and store information. One option available to users is information handling systems. An information handling system generally processes, compiles, stores, and/or communicates information or data for business, personal, or other purposes thereby allowing users to take advantage of the value of the information. Because technology and information handling needs and requirements vary between different users or applications, information handling systems may also vary regarding what information is handled, how the information is handled, how much information is processed, stored, or communicated, and how quickly and efficiently the information may be processed, stored, or communicated. The variations in information handling systems allow for information handling systems to be general or configured for a specific user or specific use such as financial transaction processing, airline reservations, enterprise data storage, or global communications. In addition, information handling systems may include a variety of hardware and software components that may be configured to process, store, and communicate information and may include one or more computer systems, data storage systems, and networking systems.
Information handling system performance has steadily increased over time as processing components have increased their ability to process greater amounts of information in reduced amounts of time. Another factor to improved information handling system performance is the greater speeds at which buses within information handling systems are able to communication information between processing components. For example, the recently introduced PCI Express bus communicates information at rates that are considerably more rapid than its predecessor PCI bus. Generally, the more rapid processing and communication of information occurs due to the increased number of transistor devices integrated within processing components to perform processing operations and the greater number of operating cycles that the processing components run per operating time period. However, the ability of processing components within an information handling system to more rapidly process information typically means that the amount of power used by the information handling system also increases. For portable information handling systems that operate on internal battery power having limited duration, the increased power consumption often translates into reduced battery life for a give battery charge.
One method for reducing power consumption of an information handling system is to place processing components in an idle state when the processing components are inactive. As an example, the PCI Express standard defines an Active State Power Management (ASPM) protocol in which transmission of characters over a PCI Express link are stopped during idle periods in order to reduce power during times of inactivity. The ASPM protocol states that an inactivity timer set at a value determinable by the processing component manufacturer determines when the communication link should transition to a low power state. Before the transition to the low power state, the PCI Express link transmits characters during times of inactivity in order to maintain the serial link synchronization, such as the synchronization of a phased lock loop (PLL). In the idle state, link synchronization is sacrificed for power savings and re-established once the link becomes active again. However, re-establishing synchronization of a PCI Express link takes some time and thus introduces some delay in the communication of information across the link. An ideal inactivity timer value for assertion of low power states at a PCI Express link depends upon link traffic patterns which vary widely depending upon the type of components involved, system activity, the application being run or other factors. Component manufacturers are motivated to select an inactivity timer value that minimizes the impact on component performance or is optimized for a give set of conditions that may differ substantially from actual operating conditions.