I-Segmenter: Integer-Only Vision Transformer for Efficient Semantic Segmentation
Martyna Poreba, Jordan Sassoon and Michal Szczepanski
Vision Transformers (ViTs) have recently achieved strong results in
semantic segmentation, yet their deployment on resource-constrained
devices remains limited due to their high memory footprint and
computational cost. Quantization offers an effective strategy to improve
efficiency, but ViT-based segmentation models are notoriously fragile
under low precision, as quantization errors accumulate across deep
encoder–decoder pipelines. We introduce I-Segmenter, the first fully
integer-only ViT segmentation framework. Building on the Segmenter
architecture, I-Segmenter systematically replaces floating-point
operations with integer-only counterparts. To further stabilize both
training and inference, we propose λ-ShiftGELU, a novel
activation function that mitigates the limitations of uniform
quantization in handling long tailed activation distributions. In
addition, we remove the L2 normalization layer and replace bilinear
interpolation in the decoder with nearest neighbor upsampling, ensuring
integer-only execution throughout the computational graph. Extensive
experiments show that I-Segmenter achieves accuracy within a reasonable
margin of its FP32 baseline (5.1% on average),while reducing model size
by up to 3.8× and enabling up to 1.2× faster inferencewith optimized
runtimes. Notably, even in one-shot PTQ with a single calibration image,
I-Segmenter delivers competitive accuracy, underscoringits practicality
for real-world deployment.
A Quantitative Type Based Framework for Synchronous System Design
Rui Chen and Ingo Sander
The design process of safety-critical embedded systems is desired to be
both practical and formal. These two requirements are consistently
satisfied in a modern type-theorybased proof assistant/language that is
increasingly accommodating general-purpose programming. A framework for
embedded system design that satisfies both requirements can therefore be
built upon such a proof assistant/language. In this paper, we present a
framework for synchronous embedded system design that addresses both
aspects (practicality and formality) by exploiting the quantitatively
typed language Idris2. Specifically, we demonstrate that leveraging the
expressiveness of quantitative type theory and the tagless final
embedding enables an embedded domain-specific language (EDSL) named SynQ
(Synchronous system design with Quantitative types) to be properly
hosted in Idris2. This then allows Idris2 to be leveraged to facilitate
synchronous system design (modelling, transformation, and
implementation) and verification. It, hence, makes the presented
framework a step towards an embedded system design methodology that is
both practical and formal.
Optimizing the Deployment of Real-Time OpenMP Applications for Energy Efficiency
Federico Aromolo, Francesco Paladino, Luca Abeni and Tommaso Cucinotta
Designing and deploying real-time computing pipelines efficiently on
modern embedded platforms is increasingly challenging due to the growing
complexity of hardware architectures, often featuring multi-core
processors, frequency scaling capabilities, heterogeneous cores for
enhanced power efficiency, and hardware accelerators. OpenMP is a
prominent tool for parallelizing applications on multi-core platforms
and is gaining increasing adoption in the domain of real-time systems.
However, providing sound performance guarantees on the timing behavior
of complex parallel computations organized as graph structures on
heterogeneous platforms such as Arm big.LITTLE, while achieving optimal
or near-optimal energy efficiency, is all but trivial. This paper
tackles this problem by proposing a methodology to deploy and analyze
both traditional parallel real-time applications and OpenMP parallel
applications, modeled as directed acyclic graphs (DAGs) and coexisting
on the same heterogeneous platform. Specifically, the approach targets
heterogeneous Arm big.LITTLE-like platforms with frequency scaling
capabilities, with the aim of minimizing energy consumption while
guaranteeing end-to-end latency constraints via schedulability
analysis. The proposed approach features an optimal solver based on a
mixed-integer quadratic constrained programming formulation, and a
computationally efficient heuristic to extract high-quality solutions
with reduced solving time.
HELIOS: Lightweight Real-Time Scheduling with Energy Readiness Guarantees
Ruizhe Qiu, Thomas Robert, Samuel Tardieu, Laurent Pautet and Frank Singhoff
Energy-harvesting embedded systems, like sensors and medical implants,
must satisfy real-time constraints under strict energy
limitations. Traditional schedulers, which prioritize timing over
energy, often fail to produce valid schedules, particularly for
nonpreemptive task models. We introduce HELIOS, a lightweight,
table-driven scheduler that treats timing and energy as joint
first-class constraints while supporting limitedpreemptive
execution. HELIOS introduces energy readiness, ensuring jobs execute
only when both temporal and energy conditions are met. The scheduling
problem is formulated as an integer linear programming (ILP) problem,
jointly optimizing task ordering, preemption points, and execution under
energy constraints. By leveraging non-preemption and energy readiness,
HELIOS maintains complexity proportional to job count. A key innovation
is the use of worst-case energy footprints to guarantee safe execution
via an energy readiness threshold. The table-driven runtime ensures
compatibility with resource-constrained kernels. Experiments demonstrate
that HELIOS achieves higher schedulability than priority-based
baselines.
A Predictible Inter-Core Communication Model for AMP on Multi-Core
Sebastien Levieux, Stephane Rubini, Frank Singhoff, Lucas Mine, Philippe Plasson, Pierre-Vincent Gouel and Lee-Roy Malac-Allain
Today's space systems, need to process a large amount of data in space,
and therefore may use multi-core architectures. To improve timing
predictability and reduce analysis complexity, they may use Asymmetric
Multi-Processing (AMP). Because cores can execute subsystems supported
by different operating systems, the overall system implementation
requires inter-core communications implemented through portable
mechanisms. In this article, we propose PrAICC (Predictible AMP
Inter-Core Communication), a predictable inter-core communication model
for multi-core heterogeneous AMP architectures. PrAICC has been designed
to enforce timing predictability while ensuring message latency
requirements. It is based on shared memory and platform-agnostic
spinlocks to ensure portability, and on polling for timing
predictability. We also propose a method to assess the schedulability of
applications communicating with PrAICC. Our evaluations showed that the
schedulability model is able to predict message latencies and task
worst-case response times. The schedulability model of PrAICC is able to
explore trade-offs between schedulability analysis pessimism and message
latency. An evaluation on the PLATO case study determined that the best
trade-off between message latencies and predictability is obtained a
polling period of 100ms. With such a period, the message latency and
the schedulability analysis pessimism are respectively bounded to
133ms and 48%.
Packet-Based Data Latency and Schedulability Optimization in Directed Acyclic Graphs of Multirate Automotive Cause-Effect Chains
Muhammad Tanveer Ali Ahmad, Jesus Pestana and Marcel Baunach
AUTOSAR-based automotive software decomposes applications into sequences
of runnables executing at different rates and linked by causal
dependencies (named cause-effect chains) to realize functionalities,
such as sensor-to-actuator interactions. In practice, an application
contains multiple cause-effect chains that share runnables and thus form
a directed acyclic graph (DAG). Meeting stringent end-to-end timing
requirements (e.g., reaction time) while using resources efficiently
depends strongly on how runnables are grouped into tasks and how tasks
are released and scheduled. We present an automated approach that
jointly determines runnable-to-task mapping, the execution order of
runnables within each task, and task offsets, while preserving
schedulability. To analyze end-to-end packet-based data latencies
precisely, we introduce a packet-oriented method based on symbolic
execution. It provides accurate and explainable timing analysis for
reaction time, data age, and time disparity. Unlike existing methods
that treat each cause-effect chain independently, our analysis considers
the full runnable DAG and naturally supports merged multirate
cause-effect chains. Together, the proposed design and analysis
techniques support correct-bydesign early-stage modeling of automotive
applications. Experiments on industrial case studies and automotive
benchmarks show that our approach yields tighter latency estimates than
state-of-the-art methods while improving explainability.
Task-to-Accelerator Mapping for Predictable OpenMP Applications
Mohammad Samadi, Tiago Carvalho, Luís Miguel Pinho and Sara Royuela
OpenMP offers a high-level, portable programming model that simplifies
the expression of parallelism and offloading in heterogeneous platforms,
making it an ideal framework for managing task execution across CPUs and
GPUs. However, as applications increasingly require predictability and
multi-GPU execution, the lack of predictability in current OpenMP
scheduling mechanisms poses significant challenges. Irregular
workloads, variable data transfers, and dynamic resource contention
often lead to inconsistent response times and reduced timing
determinism. This unpredictability limits system efficiency and
reliability, particularly in performancecritical and real-time
domains. To overcome the challenge mentioned above, this paper proposes
an efficient task-to-accelerator mapping (i.e., assigning tasks to GPU
devices for execution) for multi-GPU OpenMP applications. The mechanism
includes an offloading manager that operates a global queue and multiple
local queues, and different heuristic algorithms that first allocate
tasks to the most appropriate queues and then select the most suitable
tasks from each queue. The proposed heuristics aim to balance queue
loads and enhance the work-conserving property of the mapping process to
minimize response time and response-time variability. The paper also
presents a thorough evaluation using both synthetic graphs and graphs
representative of real-world applications, showing that the proposed
mapping method outperforms the other relevant mapping.
Minimal simulation interval for periodic task schedulers
Damien Guidolin-Pina, Emmanuel Grolleau, Frank Singhoff and Hai Nam Tran
Simulation-based analysis is widely used to evaluate the temporal
behavior of real-time systems, but its effectiveness depends on
determining a finite simulation horizon after which the schedule repeats
cyclically. Existing cyclicity bounds are often overly conservative or
restricted to narrow classes of scheduling algorithms, and many tools
still rely on seminal bounds that significantly overestimate the
required simulation duration. In this paper, we introduce a new generic
class of schedulers, called Resettable Deterministic Schedulers. This
class strictly extends the deterministic and memoryless schedulers
studied in the literature while also including non-memoryless algorithms
such as Round-Robin. For this class, we establish an exact cyclicity
result for work-conserving schedules of periodic task systems whose
processor utilization does not exceed one. We prove that any such
schedule becomes cyclic with a period equal to the system
hyperperiod. The end of the first cycle is the first idle instant
occurring after task releases become periodic, denoted t0. We derive a
tight upper bound on this instant equal to t0+H(1+U), where U is the
processor utilization, and H is the hyperperiod. When offsets are
smaller than periods, the bound simplifies to H(1+U). The result
requires no feasibility assumption and halves the simulation length in
Cheddar.
Dependable software engineering: Can we increase trust in our components?
Marcelo Pasin, Kleiton Pereira, Titus Abele, Guilherme Piêgas Koslovski and Thomas Niederberger
The complexity of the modern Software Supply Chain (SSC) introduces
significant risks regarding the provenance and integrity of third-party
dependencies. Current composition solutions often lack granular
visibility into the artifacts they execute, relying on implicit trust in
centralized registries. This paper introduces a security architecture
designed to enforce explicit trust in software compositions. We define
the concept of Verifiable Components, which bundle executable bytecode
with cryptographically signed Software Bills of Materials (SBOMs) and
audit metadata. Leveraging the nested structure of the WebAssembly
Component Model, we propose a recursive verification protocol that
validates the integrity of the entire dependency tree at runtime. We
provide a formal proof using structural induction to demonstrate that,
under standard cryptographic assumptions, our protocol eliminates the
possibility of component tampering or masquerading. Furthermore, we
present Wasmshield, a Rust-based prototype integrated with the Wasmtime
runtime. Our evaluation shows that while generating verifiable
components incurs a compilation overhead of approximately 42%, the
architecture provides robust, runtime-agnostic integrity guarantees that
effectively mitigate supply chain attacks.