David Siorpaes

2PARMA: Parallel Paradigms and Run-Time Management Techniques for Many-Core Architectures

The main goals of the 2PARMA project are: the definition of a parallel programming model combining component-based and single-instruction multiple-thread approaches, instruction set virtualisation based on portable byte-code, run-time resource management policies and mechanisms as well as design space exploration methodologies for many-core computing architectures.

GORA: Goodput Optimal Rate Adaptation for 802.11 Using Medium Status Estimation

Rate adaptation for 802.11 has been deeply investigated in the past, but the problem of achieving optimal rate adaptation with respect not only to channel-related errors but also to contention-related issues (i.e., collisions and variations in medium access times) is still unsolved. In this paper we address this issue by proposing (1) a practical definition of the medium status in a multi-user 802.11 scenario in terms of channel errors, MAC collisions and packet service times, and a method for its estimation based on measurements; (2) an analytical model of the goodput performance as a function of the Medium Status; (3) a rate adaptation algorithm, called goodput optimal rate adaptation (GORA), which is based on this model. Unlike other rate adaptation schemes proposed in literature, which require either modifications to the IEEE 802.11 standard or cooperation among nodes, GORA is totally stand-alone and standard compliant. In fact, the Medium Status Estimation used by GORA is obtained by using standard MAC counters that are commonly collected by commercial MAC drivers, and no explicit interactions with the other devices in the network is required. Therefore, GORA offers the advantage of being readily deployable on real devices. The performance of GORA is evaluated through NS2 simulations which reveal that, as expected, GORA outperforms other well- known rate adaptation algorithms in several scenarios and can be used as a new reference benchmark.

Predictive models for multimedia applications power consumption based on use-case and OS level analysis

Power management at any abstraction level is a key issue for many mobile multimedia and embedded applications. In this paper a design workflow to generate system-level power models will be presented, tailored to support quantitative run-time power optimization policies to be implemented within an operating system. The approach we followed to derive power models is strongly use-case oriented. Starting from a comprehensive general and accurate model of a representative architecture for embedded applications (including a multi core MPSoC, accelerators, interfaces and peripherals), a methodology to derive compact models is presented, based upon the distinctive characteristics of the selected use cases. The methodology to generate such model, whose exploitation is foreseen within a power manager working at the OS level, is the focus of the paper. The value and accuracy of the approach is quantitatively and statistically justified through extensive experiments carried out on a development board designed for multimedia applications.

Parallel paradigms and run-time management techniques for many-core architectures: the 2PARMA approach

The 2PARMA project aims at overcoming the lack of parallel programming models and run-time resource management techniques to exploit the features of many-core processor architectures. More in detail, the 2PARMA project focuses on the definition of a parallel programming model combining component-based and single-instruction multiple-thread approaches, instruction set virtualisation based on portable byte-code, run-time resource management policies and mechanisms as well as design space exploration methodologies for Many-core Computing Fabrics.

Parallel paradigms and run-time management techniques for many-core architectures: The 2PARMA approach

The 2PARMA project aims at overcoming the lack of parallel programming models and run-time resource management techniques to exploit the features of many-core processor architectures. More in detail, the 2PARMA project focuses on the definition of a parallel programming model combining component-based and single-instruction multiple-thread approaches, instruction set virtualisation based on portable byte-code, run-time resource management policies and mechanisms as well as design space exploration methodologies for Many-core Computing Fabrics.

A hierarchical distributed control for power and performances optimization of embedded systems

Power and resource management are key goals for the success of modern battery-supplied multimedia devices. This kind of devices are usually based on SoCs with a wide range of subsystems, that compete in the usage of shared resources, and offer several power saving capabilities, but need an adequate software support to exploit such capabilities. In this paper we present Constrained Power Management (CPM), a cross-layer formal model and framework for power and resource management, targeted to MPSoC-based devices. CPM allows coordination and communication, among applications and device drivers, to reduce energy consumption without compromising QoS. A dynamic and multi-objective optimization strategy is supported, which has been designed to have a negligible overhead on the development process and at run-time.

APOS: Adaptive Parameters Optimization Scheme for Voice over IEEE 802.11g

In this paper we present APOS, a method for dynamically adapting the parameters of IEEE 802.11 g to the estimated system state, with the aim of enhancing the quality of a voice communication between a mobile station and a remote peer node. The system state is estimated based on a number of counters that are collected by the MAC layer of the mobile station, regarding the number of successful and unsuccessful transmission/reception events, channel busy periods and idle slots. These statistics are processed to estimate the collision probability and the signal to noise ratio at the receiver side. Hence, a mathematical model is used to get the expected end-to-end network performance in terms of throughput, delay and packet error rate, for different settings of some PHY and MAC parameters, such as the modulation/coding scheme and the retransmission limit. The setting that is estimated to maximize the quality of service for the end user is then selected. Unlike other optimization mechanisms proposed in literature, APOS is totally stand-alone and standard compliant. In fact, APOS makes use of local information that can be collected from the Network Interface Card, and no explicit interactions with the other devices in the network is required.