Electrical computers and digital processing systems: multicomput – Computer-to-computer data routing – Least weight routing
Reexamination Certificate
1997-03-06
2001-10-09
Banankhah, Majid (Department: 2151)
Electrical computers and digital processing systems: multicomput
Computer-to-computer data routing
Least weight routing
C709S241000, C709S241000
Reexamination Certificate
active
06301602
ABSTRACT:
BACKGROUND OF THE INVENTION
This invention relates to a priority information display system that displays information on the priorities of processes effective in debugging, for example, a concurrent program.
In a concurrent-program execution environment, priority is generally set for units of concurrent operations, called tasks, processes, or objects, (hereinafter, referred to as “processes”). Priority is set for each process. Each process operates concurrently with other processes according to the scheduling from the operating system. As a general rule, in a specific operating system where priority is changed dynamically, the higher the priority of a process, the sooner the process will be executed.
In recent years, an operating system with a priority inheritance algorithm that causes a process to inherit the priority of another process has been provided. In priority inheritance by the algorithm, the present priority of the process that is to inherit priority is changed dynamically to the priority of the process from which the priority is inherited.
Explanation will be given, provided that a single process has a “initial basic priority”, a “basic priority”, and a “present priority”. The “initial basis priority” means the value of priority given to a process in the initial stage and remains unchanged, as a general rule. The “basic priority” means the value of priority that changes only due to a specific factor (a specific system call) excluding the priority inheritance, as a general rule. The “present priority” means the value of priority that the operating system uses in scheduling, as a general a rule. The value of the present priority changes, depending on various factors including priority inheritance.
Some dynamic changes of priority are related to inheritance and other dynamic changes of priority are not related to inheritance. In the former case, that is, when dynamic changes of priority are related to inheritance, the factors triggering the change of priority include, for example, the issue of an interprocess synchronizing system call and the occurrence of an event, such as message exchange.
In the latter case, the change of the basic priority is taken as example.
A single process has “process states”.
The “process states” mean the states of a process scheduled by the scheduler in the operating system.
Here, they indicate three states distinguished from each other by “Ready,” “Wait,” and “Run.”
In the environment for debugging concurrent programs executed on the operating system using the priority inheritance algorithm, the desired program is debugged by recording the history of events occurred during the execution of the program and observing the behavior of the process.
The known methods of displaying information on priority, such as the current priority or the basic priority, include a method of recording the value of priority after the change at the time of issuing a priority change system call and a method of checking the priorities in unison with a specific timing. With these methods, however, the obtained priorities are only displayed in numerical values, which makes it impossible to display information on priority inheritance effectively.
BRIEF SUMMARY OF THE INVENTION
It is, accordingly, an object of the present invention to overcome the disadvantage in the prior art by providing the following priority information display systems:
(1) A priority information display system that displays information on priority effective in debugging concurrent programs or the like.
(2) A priority information display system that displays the priority information three-dimensionally so as to provide the user with the priority information effectively.
The foregoing objects are accomplished by providing a priority information display system which operates with an operating system that controls an execution of a plurality of processes having their respective priorities and enables an inheritance of priority between said processes, said priority information display system comprising:
acquisition means for acquiring from said operating system a priority information including information on the inheritance of the priorities between said processes; and
display means for displaying said priority information acquired by said acquisition means.
According to the present invention, when a specific event related to the priorities of processes has taken place, not only specific process information on the event can be acquired and displayed, but also the behavior of processes, the change of priority, the cause of priority change, etc. can be recorded and displayed to the user, so that the user can easily find bugs or the like in the application program stemming from priority inheritance caused by an unexpected behavior of the process. Therefore, it is possible to provide a priority information display system that displays the program information effective in debugging the concurrent program.
Additional objects and advantages of the present invention will be set forth in the description which follows, and in part will be obvious from the description, or may be learned by practice of the present invention.
The objects and advantages of the present invention may be realized and obtained by means of the instrumentalities and combinations particularly pointed out in the appended claims.
REFERENCES:
patent: 5158686 (1992-10-01), Chastain et al.
patent: 0610581 A2 (1994-08-01), None
patent: 7-110781 (1995-04-01), None
“Priority Inheritance Protocols: An Approach to Real-Time Synchronization”, Lui Sha et al, IEEE 1990.
Banankhah Majid
Banner & Witcoff , Ltd.
Kabushiki Kaisha Toshiba
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