| dc.contributor.author | Jutla, Dawn Natalie. | en_US |
| dc.date.accessioned | 2014-10-21T12:37:41Z | |
| dc.date.available | 1996 | |
| dc.date.issued | 1996 | en_US |
| dc.identifier.other | AAINQ31529 | en_US |
| dc.identifier.uri | http://hdl.handle.net/10222/55546 | |
| dc.description | In recent years, there has been an increasing number of applications that efficiently use virtual memory for access control purposes. In many cases, improved application performance has been attained when the protection unit size is different from that of a system page. Improved application performance has also been achieved through the provision of alternative access control protocols per application within a computer system. The advent of 64-bit architectures has caused the issue of maintaining isolation among threads working in a single address space to assume new importance. | en_US |
| dc.description | This dissertation presents a novel virtual memory model which provides efficiencies to applications in terms of variable-sized protection units, customizability of access control service per region of memory, access control handling without the use of software handlers, synchronization at the level of threads, and fault isolation. These features are accomplished by imposing views on the regions of memory. Applications are provided with the flexibility of selecting from a large range of access control units' sizes (sizes must be powers of two). Protocols are implemented as fully as possible by table lookups. The potential reloading of the tables facilitates the customizability of the operating system control services. Synchronization at the level of threads and the maintenance of the views on the regions of memory facilitate fault isolation. | en_US |
| dc.description | The widespread applicability of the model is demonstrated, in the thesis, by illustrating support for a number of access control protocols. The protocols are decomposed into state transitions, and these descriptions are supported by a cache-based protection architecture. | en_US |
| dc.description | A qualitative analysis is performed to compare the performance of the proposed system with the performance of a traditional scheme. A quantitative performance study is conducted to compare the costs, in terms of machine cycles, of performing access control determination through the conventional method as opposed to using the virtual memory model with the chosen protection architecture and operating system support. | en_US |
| dc.description | Results from the performance study show an overall improvement over other schemes in terms of cycle times. Much of this is due to a reduction in the frequency of faulting to software handlers, lesser complexity in maintaining status of shared data and non pollution of the TLB and primary data caches. The implementation of access control as shown in this thesis results in an increased hit rate in the TLB cache which is a critical factor to enhancing applications' overall performance. | en_US |
| dc.description | Thesis (Ph.D.)--DalTech - Dalhousie University (Canada), 1996. | en_US |
| dc.language | eng | en_US |
| dc.publisher | Dalhousie University | en_US |
| dc.publisher | | en_US |
| dc.subject | Computer Science. | en_US |
| dc.title | Multiview model for protection and access control. | en_US |
| dc.type | text | en_US |
| dc.contributor.degree | Ph.D. | en_US |
