Electrical computers and digital data processing systems: input/ – Input/output data processing – Peripheral configuration
Reexamination Certificate
1998-08-26
2001-01-09
Etienne, Ario (Department: 2781)
Electrical computers and digital data processing systems: input/
Input/output data processing
Peripheral configuration
C710S010000, C710S108000, C710S104000, C710S108000
Reexamination Certificate
active
06173341
ABSTRACT:
BACKGROUND OF THE INVENTION
1. Field of the Invention
The present invention relates to computer systems with novel input-output (I/O) architectures, and more particularly, and not by way of limitation, to a plug-and-play control mechanism for assigning and controlling one or more adapters.
2. Description of Related Art
A conventional computer system typically includes one or more central processing units (CPUs) capable of executing algorithms and one or more memory subsystems. Computer systems also include peripheral devices, or, peripherals, for inputting and outputting data. Some common peripheral devices include, for example, monitors, keyboards, printers, modems, hard disk drives, floppy disk drives, and network controllers. As known in the art, peripheral devices may be conveniently categorized into several classes based on their functionality. For example, the “block storage device” class of peripherals may include hard disk drives, whereas the “Local Area Network (LAN) ports” class may include LAN controllers, such as, for example, Ethernet controllers. The various components of a computer system communicate and transfer data using a bus system which is connected to the communicating components.
One of the key factors in the performance of a computer system is the speed at which the CPU operates. Generally, the faster the CPU operates, the faster the computer system can complete a designated task. Another method of increasing the speed of a computer system is using multiple CPUs, commonly known as multi-processing. With multiple CPUs, algorithms required to complete a task can be executed substantially in parallel as opposed to their sequential execution.
However, the addition of a faster CPU or additional CPUs can result in different increases in performance among different computer systems. Although it is the CPU that executes the algorithms required for performing a designated task, in many cases, it is the peripherals that are responsible for providing data to the CPU and storing or outputting the processed data from the CPU. When a CPU in operation attempts to read or write to a peripheral, the CPU often “sets aside” the algorithm which it is currently executing and is diverted to executing the read/write transaction (also referred to as an Input/Output transaction, or an I/O transaction) for the peripheral. As can be appreciated by those skilled in the art, the length of time that the CPU is diverted is typically dependent on the efficiency of the I/O transaction.
Although a faster CPU may accelerate the execution of an algorithm, a slow or inefficient I/O transaction process associated therewith would create a bottleneck in the overall performance of the computer system. As the CPU becomes faster, the amount of time executing algorithms becomes less of a limiting factor compared to the time expended in performing an I/O transaction. Accordingly, the improvement in the performance of the computer system that could theoretically result from the use of a faster CPU or the addition of another CPU may become substantially curtailed by the bottleneck created by I/O transactions. Moreover, it can be readily appreciated that any performance degradation due to such I/O bottlenecks in a single computer system may have a stifling effect on the overall performance of a computer network in which the computer system is disposed.
Operating peripheral devices in association with a computer system typically requires a piece of executable code, known commonly as a device driver. Because peripherals are often manufactured separately from the CPU, the operation of a peripheral is generally effectuated by a unique device driver associated with the specific peripheral. The device driver, which controls the peripheral, is an executable computer program that is executed by the CPU and must be compatible with the particular operating system (OS) of the computer system. It can be readily seen that because device drivers are unique to both operating systems as well as peripherals, a considerable number of device drivers are typically required to support the numerous possible combinations of peripherals and operating systems. Accordingly, it can be appreciated that the ensuing device driver proliferation thwarts the objective of device driver portability in the design of cross-platform computer system architectures.
Based on the foregoing discussion, it should be appreciated that current computer systems with a conventional I/O architecture utilizing device drivers described above suffer from a lack of device driver portability and performance constraints due to I/O bottlenecks. In order to address these shortcomings, an alternative I/O architecture—commonly known as the Intelligent Input/Output (I
2
O) architecture—has been developed in the computer industry. Because the teachings of the present invention may be better described in relation to the I
2
O architecture, a brief overview thereof is provided hereinbelow.
Essentially, the I
2
O architecture uses a “split driver” model which inserts a messaging layer between the portion of the device driver specific to the operating system and the portion of the device driver specific to the peripheral device. It should be appreciated that in the parlance of the I
2
O architecture, a peripheral device is also sometimes referred to as an adapter. Accordingly, henceforth, these two terms would be used somewhat interchangeably.
The messaging layer splits the single device driver of today into two separate modules—an Operating System Service Module (OSM) and a Downloadable Driver Module (DDM). The only interaction one module has with another module is through this messaging layer which provides the communication means.
The OSM comprises the portion of the device driver that is specific to the operating system. The OSM interfaces with the operating system of the computer system (which may also be referred to in the art as the “host operating system”) and is executed by the host CPU or processor. Typically, a single OSM may be used to service a specific class of peripherals or adapter. For example, one OSM would be used to service all block storage devices, such as hard disk drives and CD-ROM drives. The DDM provides the peripheral-specific portion of the device driver that understands how to interface to the particular peripheral hardware. To execute the DDM, an I
2
O Input/Output Processor (IOP) is added to the computer system. A single IOP may be associated with multiple peripherals, each controlled by a particular DDM, and containing its own operating system such as, for example, the I
2
O Real-Time Operating System (iRTOS). The DDM directly controls the peripheral, and is executed by the IOP under the management of the iRTOS.
Those skilled in the art will recognize that a DDM may typically comprise a Hardware Device Module (HDM) that directly interfaces with the peripheral and is responsible for its control and data transfer associated therewith. DDMs can also comprise an Intermediate Service Module (ISM) which is an additional software interface to the HDM. The ISM is often used for filtering, encoding, and decoding messages to the HDM.
In general operation, the communication model used in the I
2
O architecture is a message passing system. When the CPU seeks to read or write to an adapter or peripheral in an I
2
O system, the host operating system makes what is known as a “request”. The OSM translates the request by the host operating system and, in turn, generates a message. The OSM sends the message across the messaging layer to the DDM associated with the peripheral which processes it appropriately to achieve a result. Upon completion of the processing, the DDM sends the result back to the OSM by sending an appropriate message through the messaging layer. It can be appreciated that to the host operating system, the OSM appears just like any other device driver.
By executing the DDM on the IOP, the time-consuming portion of transferring information from and to the peripheral hardware is off-loaded from the CPU to the IOP. With this off-loadin
Emerson Theodore F.
McCarty Christopher J.
Compaq Computer Corporation
Etienne Ario
Fletcher Yoder & Van Someren
LandOfFree
System and method for configuring adapters in a computer system does not yet have a rating. At this time, there are no reviews or comments for this patent.
If you have personal experience with System and method for configuring adapters in a computer system, we encourage you to share that experience with our LandOfFree.com community. Your opinion is very important and System and method for configuring adapters in a computer system will most certainly appreciate the feedback.
Profile ID: LFUS-PAI-O-2465685