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- Björnfot, Lars, et al.
(författare)
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Distributed Run-Time System, a Protocol for Ada
- 1993
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Ingår i: Proc. Ada-Europe'93, LNCS 688. - Berlin, Heidelberg : Springer Berlin Heidelberg. ; , s. 249-263
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- The requirements and specification of a protocol for low level communication between the run-time systems in a distributed Ada environment is presented. This allows an Ada system to be separated into software resources and run-time controllers. Calls to the local run-time system of a node, concerning task management, are transformed into remote calls to the controller, that schedules all tasks in the application. The calls to the run-time system together with all messages, requests and replies, that are triggered as a consequence, are described. The controller will be implemented in hardware separate from the processors. Communication between processors and controllers are by means of high speed (Gigabit) networks. In the proposed system, partitioning and distribution of Ada programs can fully utilize the inherent and strong type checking in Ada.
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| 2. |
- Björnfot, Lars, et al.
(författare)
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Distribution of Tasks Within a Centrally Scheduled Local Area Network
- 1994
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Ingår i: Proc. Ada-Europe'94, LNCS 887. - Berlin, Heidelberg : Springer Berlin Heidelberg. ; , s. 421-432
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)abstract
- Distribution of a single Ada program on a local area network is accomplished by partitioning the run-time system into two parts. A central scheduling module is responsible for task management. Distributed run-time executives handle context switches and remote entry calls; however all activities are supervised by the scheduler. The scheduler can be implemented in hardware in order to achieve high efficiency. A network based on optical fibers is necessary due to the high speed required for system calls. Asynchronous Transfer Mode is suggested as the protocol for the communication. We describe an implementation of the divided run-time system on an Ethernet network, using MC68030-based micro computers as targets and an Ada program executing on a Rational host as the scheduler.
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| 5. |
- Fohler, Gerhard
(författare)
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Flexibility in Statically Scheduled Real-Time Systems
- 1994
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Doktorsavhandling (övrigt vetenskapligt/konstnärligt)abstract
- Static scheduling has been shown to be appropriate for a variety of hard real-time systems, mainly due to the verifiable timing behavior of the system and the complex task models supported. Its application is, however, impeded in systems with changing operational modes and critical activities, that arrive infrequently with unknown occurrence times. This thesis presents an approach to overcome these shortcomings. It addresses static scheduling, illustrated by an algorithm serving as case study, and provides concepts to extend the scope of statically scheduled systems to deal with mode changes properly and to provide for efficient handling of dynamic activities. Mode changes are performed by switching from one periodically executing static schedule to another via a special schedule to prepare for the change. As all involved schedules are constructed statically, all actions executing the mode change do so deterministically: Given the current mode, time, and mode change request, the exact executions during the mode change and their completion time are known before run-time. Dynamic activities are incorporated into static schedules by making use of the unused resources and leeways in the schedule. We present mechanisms to effectively maintain information about the amount of dynamic activity that can be accommodated without impairing the feasible execution of statically scheduled tasks. Ontop of this service, aperiodic tasks can be handled in a very simple way. We furthermore present an on-line guarantee algorithm. A combined approach integrates both methods.
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| 6. |
- Johansson, Lena, 1967-, et al.
(författare)
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The use of bryophytes as bioindicators
- 1994
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Ingår i: International Association of Theoretical and Applied Limnology. - Stuttgart. ; , s. 2026-2028
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Konferensbidrag (övrigt vetenskapligt/konstnärligt)
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