A monitoring unit as well as method for predicting abnormal operation of time-triggered computer systems

Abstract

The invention relates to a time-triggered computer system (800) that involves [i] a Main Processor (801) that has been designed to run one or more tasks according to one or more predetermined task schedules, only one of which, the “active task schedule”, will be active at any point in time; [ii] a Monitor Processor (802) that has been designed to determine whether the Main Processor (801) is about to execute a task that is not in accordance with the active task schedule; [iii] a Communication Link (803) for passing information about future task executions between the Main Processor (801) and the Monitor Processor (802); and [iv] a Control Mechanism (comprising a System Control output (805), and / or a Communication Link B (806), and / or a Reset Link (807)) by means of which the Monitor Processor can halt or reset the Main Processor and take other corrective actions involving devices to which the computer system is connected, if the Monitor Processor determines that the Main Processor is about to execute a task that is not in accordance with the active schedule.

Description

FIELD OF THE INVENTION[0001]The present invention relates to an apparatus and a method which provides improved reliability and security for computer systems. In particular, the present invention relates to a monitoring unit for predicting abnormal operation of a time-triggered computer system, and a method of providing such a monitoring unit.BACKGROUND TO THE INVENTION[0002]A computer system is usually comprised of one or more “Commercial Off The Shelf” (COTS) processors—for example, microcontrollers or microprocessors—and some software that will execute on such processor(s): this software may be created, for example, using a programming language such as ‘C’ or Ada.[0003]In many cases, processors are “embedded” inside larger systems, including cars, aircraft, industrial and agricultural machinery, medical equipment, white and brown goods and even in toys. It is estimated that people in the developed world encounter around 300 of such “embedded systems” every day while going about th...

AI Technical Summary

Benefits of technology

This patent is about a computer system that reduces the risk of critical failures by monitoring and controlling tasks being executed by a main processor. The system receives information about tasks that the main processor plans to execute and determines if the tasks are critical. If a critical task is planned, the system can stop or reset the main processor to prevent the task from being executed. Additionally, the system ensures that tasks are balanced to prevent execution time differences. This technical effect is an improved reliability and stability of the computer system.

Problems solved by technology

In most (but not all) cases, the lockstep solution will involve two or more processor units in close proximity: this gives rise to concerns about common-mode faults: for example, physical damage, vibration, humidity or radiation sources may have a similar impact on all processor units, causing errors to go undetected.

If we can avoid such common-mode failures, lockstep processors may allow us to detect the impact of some errors (including, potentially, the impact of EMI), but they provide little or no protection against programming errors (including residual errors), or program changes (caused, for example, by viruses or deliberate tampering).

Such watchdogs typically enforce a system halt or reset if they are not “fed” at the required frequency (and it is assumed—often implicitly—that system errors will interfere with this feeding process).

By the time such changes are significant enough to be detected, a great deal of damage may already have been done.

Late detection of errors in aerospace systems, industrial systems, defence systems, medical systems, financial systems or even household goods may also result in injury, loss of human life and / or very significant financial losses.

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