Computation of Buffer Capacities for Throughput Constrained and Data Dependent Inter-Task Communication

Streaming applications are often implemented as task graphs. Currently, techniques exist to derive buffer capacities that guarantee satisfaction of a throughput constraint for task graphs in which the inter-task communication is data-independent, i.e. the amount of data produced and consumed is independent of the data values in the processed stream. This paper presents a technique to compute buffer capacities that satisfy a throughput constraint for task graphs with data dependent inter-task communication, given that the task graph is a chain. We demonstrate the applicability of the approach by computing buffer capacities for an MP3 playback application, of which the MP3 decoder has a variable consumption rate. We are not aware of alternative approaches to compute buffer capacities that guarantee satisfaction of the throughput constraint for this application

Buffer Capacity Computation for Throughput Constrained Streaming Applications with Data-Dependent Inter-Task Communication

Streaming applications are often implemented as task graphs, in which data is communicated from task to task over buffers. Currently, techniques exist to compute buffer capacities that guarantee satisfaction of the throughput constraint if the amount of data produced and consumed by the tasks is known at design-time. However, applications such as audio and video decoders have tasks that produce and consume an amount of data that depends on the decoded stream. This paper introduces a dataflow model that allows for data-dependent communication, together with an algorithm that computes buffer capacities that guarantee satisfaction of a throughput constraint. The applicability of this algorithm is demonstrated by computing buffer capacities for an H.263 video decoder

Architecture Design Space Exploration for Streaming Applications Through Timing Analysis

In this paper we compare the maximum achievable throughput of different memory organisations of the processing elements that constitute a multiprocessor system on chip. This is done by modelling the mapping of a task with input and output channels on a processing element as a homogeneous synchronous dataflow graph, and use maximum cycle mean analysis to derive the throughput. In a HiperLAN2 case study we show how these techniques can be used to derive the required clock frequency and communication latencies in order to meet the application's throughput requirement on a multiprocessor system on chip that has one of the investigated memory organisations

Experience with the ZEUS trigger system

The first three years' running experience of the ZEUS trigger system is reviewed. A three level trigger system was built to cope with the high frequency collisions and the high background rates. In 1994 the design performance was almost achieved at each level. The system is flexible enough to match the physics needs that change with increasing luminosity

Simultaneous Budget and Buffer Size Computation for Throughput-Constrained Task Graphs

Modern embedded multimedia systems process multiple concurrent streams of data processing jobs. Streams often have throughput requirements. These jobs are implemented on a multiprocessor system as a task graph. Tasks communicate data over buffers, where tasks wait on sufficient space in output buffers before producing their data. For cost reasons, jobs share resources. Because jobs can share resources with other jobs that include tasks with data-dependent execution rates, we assume run-time scheduling on shared resources. Budget schedulers are applied, because they guarantee a minimum budget in a maximum replenishment interval. Both the buffer sizes as well as the budgets influence the temporal behaviour of a job. Interestingly, a trade-off exists: a larger buffer size can allow for a smaller budget while still meeting the throughput requirement. This work is the first to address the simultaneous computation of budget and buffer sizes. We solve this non-linear problem by formulating it as a second-order cone program. We present tight approximations to obtain a non-integral second-order cone program that has polynomial complexity. Our experiments confirm the non-linear trade-off between budget and buffer sizes

Dataflow Analysis for Multiprocessor Systems with Non-Starvation-Free Schedulers

Dataflow analysis techniques are suitable for the temporal analysis of real-time stream processing applications. However, the applicability of these models is currently limited to systems with starvation-free schedulers, such as Time-Division Multiplexing (TDM) schedulers. Removal of this limitation would broaden the application domain of dataflow analysis techniques significantly. In this paper we present a temporal analysis technique for Homogeneous Synchronous Dataflow (HSDF) graphs, that is also applicable for systems with non-starvation-free schedulers. Unlike existing dataflow analysis techniques, the proposed analysis technique makes use of an enabling-jitter characterization and iterative fixed-point computation. The presented approach is applicable for arbitrary (cyclic) graph topologies. Buffer capacity constraints are taken into account during the analysis and sufficient buffer capacities can be determined afterwards. The approach presented in this paper is the first approach that considers non-starvation-free schedulers in combination with arbitrary HSDF graphs. The proposed dataflow analysis technique is implemented in a tool. This tool is used to evaluate the analysis technique using examples that illustrate some important differences with other temporal analysis methods. The case-study discusses how the method presented in this paper can be used to solve a problem with the inaccuracy of the temporal analysis results of a real-time stream processing system. This stream processing system consists of an FM receiver together with a DAB receiver application which both share a Digital Signal Processor (DSP)

Interventions in sports settings to reduce risky alcohol consumption and alcohol-related harm: a systematic review

Background: Elevated levels of risky alcohol consumption and alcohol-related harm have been reported for sportspeople and supporters compared to non-sporting populations. Limited systematic reviews have been conducted to assess the effect of interventions targeting such behaviours. Methods: A review was undertaken to determine if interventions implemented in sports settings decreased alcohol consumption and related harms. Studies were included that implemented interventions within sports settings; measured alcohol consumption or alcohol-related injury or violence and were either randomised controlled trials, staggered enrolment trials, stepped-wedged trials, quasi-randomised trials, quasi-experimental trials or natural experiments. Studies without a parallel comparison group were excluded. Studies from both published and grey literature were included. Two authors independently screened potential studies against the eligibility criteria, and two authors independently extracted data from included studies and assessed risk of bias. The results of included studies were synthesised narratively. Results: The title and abstract of 6382 papers and the full text of 45 of these papers were screened for eligibility. Three studies met the inclusion criteria for the review. One of the included studies was a randomised controlled trial (RCT) of a cognitive-behavioural intervention with athletes within an Olympic training facility in the USA. The study reported a significant change in alcohol use between pre-test and follow-up between intervention and control groups. The other two studies were RCTs in community sports clubs in Ireland and Australia. The Australian study found a significant intervention effect for both risky alcohol consumption at sports clubs and overall risk of alcohol-related harm. The Irish study found no significant intervention effect. Conclusions: A limited number of studies have been conducted to assess the effect of interventions implemented in sports settings on alcohol consumption and related harms. While two of the three studies found significant intervention effects, it is difficult to determine the extent to which such effects are generalisable. Further controlled trials are required in this setting. Systematic review registration: PROSPERO CRD4201400173