Técnicas Arquitectónicas de Entrada/Salida para Sistemas Operativos Integrados

1 June, 2016


In this thesis we propose an I/O architecture for integrated systems, those which are prepared to serve real-time clients and regular clients altogether.
The proposed architecture is composed of two main components:
A multipolicy disk scheduler.
A multipolicy cache manager.

The disk scheduler proposed in this thesis contains several request queues grouped in two levels. The first level contains a queue for each kind of requests involved. The second level only have one queue that is in charge of getting the chosen requests from the first level and send them to the disk. The disk scheduler algorithm proposed involves sorting and prior discarding techniques. This allows that the number of served requests for each kind could be proportional lo the amount of resources reserved. Furthermore the algorithm takes care of the request deadline, where the requests have temporal requirements.
The cache manager proposed in this thesis uses several replacement lists to manage the blocks, one list for each kind of requests. This allows to configure the cache behavior for each kind of task, The cache algorithm selects the replacement list where the following block would be extracted.
Moreover, two new specialized cache algorithms aimed for multimedia streams have been proposed. These algorithms can be included in the multipolicy cache manager. An interval-based algorithm is proposed, aimed for constant-bit-rate streams. In this thesis we prove analytically that this algorithm reaches the maximum performance for a system with only one disk. An algorithm based on a cycle-guided block replacement is also proposed, aimed for variable-bit-rate streams. Both algorithms has been adapted to improve its performance in a system with several disks
The evaluation performed shows that the proposed solution can keep the relation between the reserved resources and the relative performance obtained for each kind of requests That goal is reached without forgetting the global performance of the whole system. Furthermore, it shows that the proposed system is flexible enough to work with any configuration.


author={Javier Fernández Muñoz},
title={Técnicas Arquitectónicas de Entrada/Salida para Sistemas Operativos Integrados},
school={Universidad Carlos III de Madrid}