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An RTOS allowing the gradual migration - TRON Project Symposium, 1992. Proceedings., Ninth
| Content Provider | Semantic Scholar |
|---|---|
| Author | Fukuda, Masahiro Nokubi, Hirotaka |
| Copyright Year | 2004 |
| Abstract | This paper describes an Real-time operating system (RTOS) which can allow users to achieve the gradual migration from the ITRON [l] kernel to the pITRON [2] kernel. It has some risks for the user to migrate between the two ITRONs because each kernel has a dierent system call specification. The p ITRON promises to speed. The ITRON, on the other hand, provides functionality to make robust programs managing complez application area. We are successfully developing a new RTOS which has two system call interfaces for the user migration between the two ITRONs with no risk. Our new RTOS allows users to achieve functional mig,mtion from the ITRON to the pITRON while both using the ITRON interface and gettting nearly the pITRON speed. 1 The p1TRON specification feature A speed oriented design is applied to build the pITRON specification which provides relatively fast system calls. Main strategies in order to get relatively fast system calls are both to eliminate timeout operation from system calls which wait the kernel resources such as the waisem() system call and to restrict the number of resources to be treated by the system calls to one. These strategies speed almost all the pITRON system calls up. No Task Control Block (TCB) is linked into both the timeout queue and the kernel resource wait queue because the pITRON specification does not permit resource wait with timeout option. The pITRON specification reduces the operations to be performed atomically by the system call such as the terfsk(), wup-tsk(), and etc. All what the ter-tsk() system call and the others have to perform is just to unlink the TCB from either the kernel resource wait queue or the timeout queue. Never both queues are to be unlinked at any system call. An RTOS allowing the gradual migration 1063-6749/92 $3.00 81992 IEEB Hirotaka Nokubi Common Software Department NEC Microcomputer Technology, Ltd Tokyo, Japan 108 The ITRON TCB, on the other hand, may be linked into both the timeout queue and the kernel resource wait queue because the ITRON kernel specification permits the kernel resource wait with timeout operation. Figure 1 shows the internal model of the ITRON. It results i n that the atomic operations which consist of unlinking from both the timeout queue and the kernel resource wait queue, and of linking ready queue must be performed by the ITRON kernel. Treating singular resource unit in the pITRON specification provides the fact that all the thing which the ter-tsk() , chg,pri(), rel-wai() system calls and etc have to carry out is just to unlink TCB from either the timeout queue or the kernel resource wait queue. For example, it is not required for the terfsk() system call to examine the next TCB, even if the TCB manipulated by the ter-tsk() system call is in the head of the kernel resource queue, in order to check if the next task in the queue is satisfied or not because the semaphore, the memory pool which links some tasks into its wait queue has no resource unit. Alternatively, what the ITRON kernel system calls which can treat plural resource units must do is not only to unl ink the TCB in question from the kernel resource wait queue but also to check if the TCB is to be unlinked from timeout queue or not and but also to examine, if the TCB is in the head of the kernel resource queue, how many resource units the next TCB in the queue requires in order to determine whether the next TCB is to be unlinked from the queue (and possibly the timeout queue) because of satisfying the next TCB with the number of request resource units. 2 The ITRON specification feature A function oriented design is applied to build the ITRON Specification which provides timeout options in the system calls such as the waiflg(), waisemo, r cv-msg () , get -bl k () . |
| File Format | PDF HTM / HTML |
| Alternate Webpage(s) | https://www.computer.org/csdl/proceedings/tron/1992/2990/00/00313262.pdf |
| Language | English |
| Access Restriction | Open |
| Content Type | Text |
| Resource Type | Article |
