The energy demand of embedded systems is crucial and typically dominated by the memory subsystem. Off-the-shelf MCU platforms usually offer a wide range of memory configurations in terms of overall memory size, which may differ in the number of memory banks provided. Split memory banks have the potential to optimize energy demand, but this often remains unused in available hardware due to a lack of power management support or require significant manual effort to leverage the benefits of split-banked memory architectures. This paper proposes an approach to solve the challenge of integrating fine-grained power management support automatically, by a combined hardware/software solution for future off-the-shelf platforms. We present a method to efficiently search for an optimized code and data mapping onto the modules of split memory banks to maximize the idle times of all memory modules. To non-invasively put memory modules into sleep mode, a PC-driven power management controller (PMC) autonomously triggers transitions between power modes during embedded software execution. The evaluation of our optimization flow demonstrates that memory mappings can be explored in seconds, including the generation of the necessary PMC configuration and linker scripts. The application of PC-driven power management enables active memory modules to remain in light sleep mode for approximately 13% to 86% of the execution time, depending on the workload and memory configuration. This results in overall power savings of up to 24% in the memory banks, in terms of static and dynamic power.

This paper presents a demonstrator chip for an industrial audio event detection application developed as part of the Scale4Edge project. The project aims at enabling a comprehensive RISC-V based ecosystem to efficiently assemble well-tailored edge devices. The chip is manufactured in Globalfoundries' 22FDX technology and contains a RISC-V CPU with custom Instruction-Set-Architecture Extensions (ISAX) for fast AI and DSP processing, a low power neural network accelerator, and a scalable PLL to fulfill real-time processing requirements. By automated integration of these specialized hardware components, we achieve a speedup of ×2.15 while reducing the power by 27% compared to the unp[ntimized solution.

In this article, we rethink the dataflow processing paradigm to a higher level of abstraction to automate the generation of multi-instance compute and memory platforms with interfaces to I/O devices (sensors and actuators). Since the different compute instances (NPUs, CPUs, DSPs, etc.) and I/O devices do not necessarily have compatible interfaces on a dataflow level, an automated translation is required. However, in multidimensional dataflow scenarios, it becomes inherently difficult to reason about buffer sizes and iteration order without knowing the shape of the data access pattern (DAP) that the dataflow follows. To capture this shape and the platform composition, we define a domain-specific representation (DSR) and devise a toolchain to generate a synthesizable platform, including appropriate streaming buffers for platform-specific tensorization of the data between incompatible interfaces. This allows platforms, such as sensor edge AI devices, to be easily specified by simply focusing on the shape of the data provided by the sensors and transmitted among compute units, giving the ability to evaluate and generate different dataflow design alternatives with significantly reduced design time.

Machine learning is increasingly introduced into medical fields, yet there is limited evidence for its benefit over more commonly used statistical methods in epidemiological studies. We introduce an unsupervised machine learning framework for longitudinal features and evaluate it using sexual behaviour data from the last 20 years from over 3'700 participants in the Swiss HIV Cohort Study (SHCS). We use hierarchical clustering to find subgroups of men who have sex with men in the SHCS with similar sexual behaviour up to May 2017, and apply regression to test whether these clusters enhance predictions of sexual behaviour or sexually transmitted diseases (STIs) after May 2017 beyond what can be predicted with conventional parameters. We find that behavioural clusters enhance model performance according to likelihood ratio test, Akaike information criterion and area under the receiver operator characteristic curve for all outcomes studied, and according to Bayesian information criterion for five out of ten outcomes, with particularly good performance for predicting future sexual behaviour and recurrent STIs. We thus assess a methodology that can be used as an alternative means for creating exposure categories from longitudinal data in epidemiological models, and can contribute to the understanding of time-varying risk factors.

Over the last decade, syphilis diagnoses among men-who-have-sex-with-men (MSM) have strongly increased in Europe. Understanding the drivers of the ongoing epidemic may aid to curb transmissions. In order to identify the drivers of syphilis transmission in MSM in Switzerland between 2006 and 2017 as well as the effect of potential interventions, we set up an epidemiological model stratified by syphilis stage, HIV-diagnosis, and behavioral factors to account for syphilis infectiousness and risk for transmission. In the main model, we used 'reported non-steady partners' (nsP) as the main proxy for sexual risk. We parameterized the model using data from the Swiss HIV Cohort Study, Swiss Voluntary Counselling and Testing center, cross-sectional surveys among the Swiss MSM population, and published syphilis notifications from the Federal Office of Public Health. The main model reproduced the increase in syphilis diagnoses from 168 cases in 2006 to 418 cases in 2017. It estimated that between 2006 and 2017, MSM with HIV diagnosis had 45.9 times the median syphilis incidence of MSM without HIV diagnosis. Defining risk as condomless anal intercourse with nsP decreased model accuracy (sum of squared weighted residuals, 378.8 vs. 148.3). Counterfactual scenarios suggested that increasing screening of MSM without HIV diagnosis and with nsP from once every two years to twice per year may reduce syphilis incidence (at most 12.8% reduction by 2017). Whereas, increasing screening among MSM with HIV diagnosis and with nsP from once per year to twice per year may substantially reduce syphilis incidence over time (at least 63.5% reduction by 2017). The model suggests that reporting nsP regardless of condom use is suitable for risk stratification when modelling syphilis transmission. More frequent screening of MSM with HIV diagnosis, particularly those with nsP may aid to curb syphilis transmission.

We propose a topology-aware distributed Reader-Writer lock that accelerates irregular workloads for supercomputers and data centers. The core idea behind the lock is a modular design that is an interplay of three distributed data structures: a counter of readers/writers in the critical section, a set of queues for ordering writers waiting for the lock, and a tree that binds all the queues and synchronizes writers with readers. Each structure is associated with a parameter for favoring either readers or writers, enabling adjustable performance that can be viewed as a point in a three dimensional parameter space. We also develop a distributed topology-aware MCS lock that is a building block of the above design and improves state-of-the-art MPI implementations. Both schemes use non-blocking Remote Memory Access (RMA) techniques for highest performance and scalability. We evaluate our schemes on a Cray XC30 and illustrate that they outperform state-of-the-art MPI-3 RMA locking protocols by 81% and 73%, respectively. Finally, we use them to accelerate a distributed hashtable that represents irregular workloads such as key-value stores or graph processing.