System having device driver operates in first mode for allowing concurrent access to adapter by applications and second mode for limiting access to one application

• US 5,671,442 A
• Filed: 05/11/1995
• Issued: 09/23/1997
• Est. Priority Date: 02/12/1993
• Status: Expired due to Term

• Current Assignee: International Business Machines Corporation
• Original Assignee: International Business Machines Corporation
• Inventors: Wilhelm, George William Jr., Feeney, James William
• Primary Examiner(s): Meky, Moustafa M.
• Application Number:
  US08/437,386
• Time in Patent Office: 866 Days
• Field of Search: 395/200, 395/275, 395/500, 395/700, 395/650, 395/200.01, 395/800, 395/830, 395/834, 395/840, 395/841, 395/821-823, 395/825-826, 395/653, 395/672-674 , 395/677-678, 395/681, 395/670, 395/701
• US Class Current: 710/14
• CPC Class Codes: G06F 13/102 where the programme performs an interfacing function, e.g. device driver G06F13/105 takes precedence; scheduling within device drivers G06F9/52; contention policies within device drivers G06F9/4881
• CPC Class Codes: G06F 9/526 Mutual exclusion algorithms
• CPC Class Codes: G06F 9/545 where tasks reside in different layers, e.g. user- and kernel-space

Abstract

A data processing system gives an application running on the operating system exclusive ownership of a hardware device. The system is operable in two modes. In the first mode the application interacts with the hardware device by making use of the processing system. In this mode many layers of the processing system are involved and the interaction time with the hardware is slow and inconsistent. In the second mode, exclusive ownership of the hardware device is granted to the application by the driver. In this mode the application has direct access to the hardware device thus avoiding the involvement of the processing system layers. The application accesses and uses the driver through a low latency processor interface linked into the application program itself.

Claims

1. An information handling system, comprising:

at least two terminals; and

a communications means coupled to the at least two terminals for communicating information between at least two terminals in the information handling system;

wherein each of said terminals comprises;

a processor, for processing information to be communicated between the terminals;

an operating system for controlling the operation of the processor;

at least one application on the processor under control of the operating system;

a device driver having at least two modes of operation, a first mode of operation of the device driver allowing concurrent access to an adapter controlled by one or more applications, and a second mode of operation of the device driver which limits access to one application; and

a communications adapter controlled by the device driver;

each device driver further comprising;

means for testing a request for access to the communications adapter to determine if such request is for a first mode or a second mode of operation;

means for setting a mode indicator to a first state if a first mode of operation is detected;

means for setting a mode indicator to a second state if the second mode of operation is indicated; and

means for blocking access by other applications if the second mode of operation has been detected.

2. An information handling system according to claim 1 wherein said communication means comprises a multi-node switch for interconnecting the terminals.

3. An information handling system according to claim 1, wherein the operating system further comprises means for processing requests from concurrent applications executing in the processor for access to a communications device in a first mode, the operating system preventing conflicts between the applications and the operating system controlling applications access to the communications device;

means for processing a request by an application for access to the communications device in a second mode, the means for processing of a request for access in a second mode further comprising;

means for distinguishing the request for access in the second mode from a request for access in the first mode;

means for passing the request for access in the second mode to the device driver; and

means for blocking by the device driver requests from other applications for access to the communications device in either the first mode or the second mode.

4. An information handling system according to claim 3, wherein the application further comprises means for bypassing the operating system and accessing the communications device directly without interruption for both input and output access.

5. An information handling system, according to claim 1, wherein each terminal further comprises:

a low latency interface means for facilitating information flow between the application and the communications adapter in the second mode of operation.

6. An information handling system according to claim 5, wherein the device driver further comprises:

means for requesting access to the communications adapter in the first and second modes; and

means for releasing access to the communications adapter.

7. An information handling system according to claim 1, wherein each terminal further comprises:

a storage means further comprising an adapter address space associated with the communications adapter.

8. An information handling system, comprising:

at least two terminals;

a multi-node switch; and

a communications means coupled to the at least two terminals and to the multi-node switch for communicating information between at least two terminals in the information handling system;

wherein each of the terminals comprises;

a processor, for processing information to be communicated between the terminals;

storage means for storing information to be processed and communicated;

an operating system for controlling the operation of the terminal;

at least one application operating on the processor under control of the operating system;

a device driver having at least two modes of operation, a first mode of operation of the device driver allowing concurrent access to an adapter controlled by the device driver by one or more applications, and a second mode of operation of the device driver which limits access to the controlled adapter to one application; and

a communications adapter controlled by the device driver;

each device driver further comprising;

means for testing a request for access to the communications adapter to determine if such request is for a first mode or a second mode of operation;

means for setting a mode indicator to a second state if the second mode of operation is indicated;

means for blocking access by other applications if the second mode of operation has been detected.