Parallel computing can take many forms. From a user's perspective, it is important to consider the advantages and disadvantages of each methodology. The following project attempts to provide some perspective on the methods of parallel computing and indicate where the tradeoffs lie along the continuum. Problems that are parallelizable enable researchers to maximize the computing resources available for a problem, and thus push the limits of the problems that can be solved. Solving any particular problem in parallel will require some very important design decisions to be made. These decisions may dramatically affect portability, performance, and cost of implementing a software solution to the problem. The results gained from this work indicate that although performance improvements are indeed possible---they are heavily dependent on the application in question and may require much more programming effort and expertise to implement.

No description available.

Multicore servers in datacenter systems are routinely used to run multiple disparate application workload mixes. Analysis performed in Google's datacenters show, for instance, components (i.e., processes) of up to 19 distinct applications to be co-deployed on a single multicore node. Virtualization technology further encourages this trend, increasing platform utilization via higher levels of workload consolidation. Systems software on these shared server nodes must meet challenges that include (a) providing end-to-end performance guarantees for possibly multiple applications and delivering global platform-level properties such as platform-level power or utilization caps., (b) mediating use of shared resources efficiently while offering isolation guarantees for multiple applications running on consolidated platforms to maintain their performance properties predictably, and (c) meeting multiple dynamic competing application performance levels and platform-level properties efficiently, especially in oversubscribed systems. The goals of this thesis addresses (a)-(c) as follows: (1) by developing system-level mechanisms for addressing challenges (a)-(c), (2) by demonstrating their ability to deliver improved application performance with less variability and improved platform efficiency, and (3) by creating principles and representative methods for realizing the isolation properties sought by applications and the efficiency sought for platforms. The concrete realization of these goals is a Virtual Platforms (VP) enabled hypervisor - where per application or platform-level policy objectives are expressed at the system-level via elastic resource abstractions, which may also change dynamically during system runtime. For multiple consolidated applications (and their virtual platforms), there are methods that monitor and mediate their use of shared platform resources to deliver improved isolation for predictable performance, while Merlin: a resource allocator for shared multicore servers makes it easier to implement higher-level arbitration policies while meeting multiple performance and platform properties. As single-node multicore platforms evolve further from small numbers of homogeneous cores toward multiple sets or islands of potentially heterogeneous cores residing on a single chip, such platforms will have multiple resource managers managing their respective `islands' of resources. Though geared toward improved scalability and functionality, for applications spanning across multiple diverse resource islands to realize such opportunities, systems software must make it easier for them to interact with the island managers; and also help islands based systems achieve end-to-end performance properties via joint coordination amongst their island managers. In order to meet the challenges in maintaining performance objectives on future `scale-out' platforms, this thesis contributes inTune: a framework for inter-island operation, offering APIs and mechanisms that permit applications (and their virtual platforms) to interface with resource islands and their resource managers to jointly achieve application performance guarantees and global platform-level properties. This thesis focuses on the management of compute, physical memory and memory bandwidth resources of single node server platforms, however the methods presented in this work can be extended to other resource types including network and storage resources. InTune and Virtual-Platforms are implemented in the Xen hypervisor for x86 multi-core platforms with multiple NUMA memory nodes. Evaluation with representative parallel, web-based, and real-time applications and application mixes demonstrate the benefits of using our methods to achieve application performance and platform policy objectives.

The Resource Reservation Protocol (RSVP) is one of the proposals of the Internet Engineering Task Force (IETF) for conveying Quality of Service (QoS) related information in the form of resource reservations along the communication path. The RSVP specification (i.e. Request for Comments 2205) provides a narrative description of the protocol without any use of formal techniques. Thus, some parts of the document may be ambiguous, difficult to understand, and imprecise. So far, RSVP implementations have provided the only mechanism for validating. The cost for fixing errors in the protocol found in the implementation can be high. These disadvantages together with the fact that RSVP is complex make it a good target for formal specification and verification. This thesis formally defines the RSVP Service Specification, models RSVP using a formal method known as Coloured Petri Nets (CPNs) and attempts to verify the model. The following steps summarise the verification process of RSVP. Firstly, the RSVP service specification is derived from the protocol description and modelled using CPNs. After validating the model, the service language, which defines all the possible service primitive occurrence sequences, is generated from the state space of the model by using automata reduction techniques that preserve sequences. Secondly, RSVP is modelled using CPNs. The model is analysed for a set of behavioural properties. They include general properties of protocols, such as correct termination, and a set of new properties defined in this thesis, which are particular to RSVP. The analysis is based on the state space method. The properties are checked by querying the state graph and checking reachability among multiple nodes of its associated Strongly Connected Component (SCC) graph. As a first step, we analyse RSVP under the assumption of a perfect medium (no loss or duplication) to ensure that protocol errors are not hidden by rare events of the medium. The state space is reduced to obtain the sequences of service primitives allowed by RSVP known as the protocol language. Then, the protocol language is compared with the service language to determine if they are equivalent. The desired properties of RSVP are proved to be satisfied by the RSVP CPN model, so that the features of RSVP included in the CPN model operate as expected under our modelling and analysis assumptions. Also, the language analysis results show that RSVP service primitive occurrence sequences generated by the RSVP model are included in the proposed model of the service specification. However, some service primitive occurrence sequences generated from the service specification model are not in the protocol language. These sequences were analysed. There is strong evidence to suggest that these sequences would also appear in the protocol if the capacity of the medium in the RSVP model was marginally increased. Unfortunately, the standard reachability analysis tools would not handle this case, due to state space explosion. / Thesis (PhD)--University of South Australia, 2003

by John Tsitsiklis and Michael Athans. / Bibliography: leaf 4. / "November, 1983." Caption title. / ONR contract ONR/N00014-77-C-0532 (NR-041-519)

John Tsitsiklis and Michael Athans. / Bibliography: leaf 6. / "November, 1983." Caption title. / ONR contract ONR/N00014-77-C-0532 (NR-041-519)

Gul A. Agha. / Includes index. / Bibliography: p. 137-140.

by John F. Rockart, Christine V. Bullen, John N. Kogan. / "December 1978." Highlights of a conference held at MIT's Endicott House in Dedham, Mass., March 29-31, 1979. / Includes bibliographical references.

Christos H. Papadimitriou, John Tsitsiklis. / "November 1982." / Bibliography: leaves 8-9.

by Dimitri P. Bertsekas, John N. Tsitsiklis, Michael Athans. / "December, 1983." / Bibliography: p. 40-42. / NSF-ECS-8217668 ONR/N00014-77-C-0532(NR 041-519)