40 Search Results for "Cazorla, Francisco J."


Volume

OASIcs, Volume 47

15th International Workshop on Worst-Case Execution Time Analysis (WCET 2015)

WCET 2015, July 7, 2015, Lund, Sweden

Editors: Francisco J. Cazorla

Document
Multi-Objective Memory Bandwidth Regulation and Cache Partitioning for Multicore Real-Time Systems

Authors: Binqi Sun, Zhihang Wei, Andrea Bastoni, Debayan Roy, Mirco Theile, Tomasz Kloda, Rodolfo Pellizzoni, and Marco Caccamo

Published in: LIPIcs, Volume 335, 37th Euromicro Conference on Real-Time Systems (ECRTS 2025)


Abstract
Memory bandwidth regulation and cache partitioning are widely used techniques for achieving predictable timing in real-time computing systems. Combined with partitioned scheduling, these methods require careful co-allocation of tasks and resources to cores, as task execution times strongly depend on available allocated resources. To address this challenge, this paper presents a 0-1 linear program for task-resource co-allocation, along with a multi-objective heuristic designed to minimize resource usage while guaranteeing schedulability under a preemptive EDF scheduling policy. Our heuristic employs a multi-layer framework, where an outer layer explores resource allocations using Pareto-pruned search, and an inner layer optimizes task allocation by solving a knapsack problem using dynamic programming. To evaluate the performance of the proposed optimization algorithm, we profile real-world benchmarks on an embedded AMD UltraScale+ ZCU102 platform, with fine-grained resource partitioning enabled by the Jailhouse hypervisor, leveraging cache set partitioning and MemGuard for memory bandwidth regulation. Experiments based on the benchmarking results show that the proposed 0-1 linear program outperforms existing mixed-integer programs by finding more optimal solutions within the same time limit. Moreover, the proposed multi-objective multi-layer heuristic performs consistently better than the state-of-the-art multi-resource-task co-allocation algorithm in terms of schedulability, resource usage, number of non-dominated solutions, and computational efficiency.

Cite as

Binqi Sun, Zhihang Wei, Andrea Bastoni, Debayan Roy, Mirco Theile, Tomasz Kloda, Rodolfo Pellizzoni, and Marco Caccamo. Multi-Objective Memory Bandwidth Regulation and Cache Partitioning for Multicore Real-Time Systems. In 37th Euromicro Conference on Real-Time Systems (ECRTS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 335, pp. 2:1-2:23, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{sun_et_al:LIPIcs.ECRTS.2025.2,
  author =	{Sun, Binqi and Wei, Zhihang and Bastoni, Andrea and Roy, Debayan and Theile, Mirco and Kloda, Tomasz and Pellizzoni, Rodolfo and Caccamo, Marco},
  title =	{{Multi-Objective Memory Bandwidth Regulation and Cache Partitioning for Multicore Real-Time Systems}},
  booktitle =	{37th Euromicro Conference on Real-Time Systems (ECRTS 2025)},
  pages =	{2:1--2:23},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-377-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{335},
  editor =	{Mancuso, Renato},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2025.2},
  URN =		{urn:nbn:de:0030-drops-235807},
  doi =		{10.4230/LIPIcs.ECRTS.2025.2},
  annote =	{Keywords: Multi-objective optimization, memory bandwidth regulation, cache partitioning, partitioned scheduling, real-time systems}
}
Document
DAMA: A Dual Arbitration Mechanism for Mixed-Criticality Applications

Authors: Wafic Lawand and Rodolfo Pellizzoni

Published in: LIPIcs, Volume 335, 37th Euromicro Conference on Real-Time Systems (ECRTS 2025)


Abstract
We discuss hardware resource management in mixed-criticality systems, where requestors may issue latency-critical (LTC) and non-latency-critical (NLTC) requests. LTC requests must adhere to strict latency bounds imposed by safety-critical applications, but timely servicing NLTC requests is necessary to maximize overall system performance in the average case. In this paper, we address this tradeoff for a shared memory resource by proposing DAMA, a dual arbitration mechanism that imposes an upper bound on the cumulative latency of LTC requests without unduly impacting NLTC performance. DAMA comprises a high-performance arbiter, a real-time arbiter, and a mechanism that constantly monitors the cumulative latency of requests suffered by each requestor. DAMA primarily executes in high-performance mode and only switches to real-time mode in the rare instances when its incorporated mechanism detects a violation of a task’s timing guarantee. We demonstrate the effectiveness of our arbitration scheme by adapting a predictable prefetcher that issues NLTC requests and attaching it to the L1 caches of our cores. We show both formally and experimentally that DAMA provides timing guarantees for LTC requests while processing other NLTC requests. We also demonstrate that with a negligible overhead of less than 1.5% on the cumulative latency bound of LTC requests, DAMA can achieve an equivalent average performance to a prefetcher that processes requests under a high-performance arbitration scheme.

Cite as

Wafic Lawand and Rodolfo Pellizzoni. DAMA: A Dual Arbitration Mechanism for Mixed-Criticality Applications. In 37th Euromicro Conference on Real-Time Systems (ECRTS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 335, pp. 9:1-9:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{lawand_et_al:LIPIcs.ECRTS.2025.9,
  author =	{Lawand, Wafic and Pellizzoni, Rodolfo},
  title =	{{DAMA: A Dual Arbitration Mechanism for Mixed-Criticality Applications}},
  booktitle =	{37th Euromicro Conference on Real-Time Systems (ECRTS 2025)},
  pages =	{9:1--9:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-377-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{335},
  editor =	{Mancuso, Renato},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2025.9},
  URN =		{urn:nbn:de:0030-drops-235875},
  doi =		{10.4230/LIPIcs.ECRTS.2025.9},
  annote =	{Keywords: Real-time Systems, Mixed-criticality Applications, Memory controllers, Prefetchers}
}
Document
Detecting Low-Density Mixtures in High-Quantile Tails for pWCET Estimation

Authors: Blau Manau, Sergi Vilardell, Isabel Serra, Enrico Mezzetti, Jaume Abella, and Francisco J. Cazorla

Published in: LIPIcs, Volume 335, 37th Euromicro Conference on Real-Time Systems (ECRTS 2025)


Abstract
The variability arising from sophisticated hardware and software solutions in cutting-edge embedded products causes software to exhibit complex execution time distributions. Mixture distributions can happen, with different density (weight), as a result of inherent different features in the execution platform and multiple operational scenarios. In the context of probabilistic WCET (pWCET) analysis based on Extreme Value Theory (EVT), where identical distribution is a pre-requisite, mixtures are typically intercepted by applying stationarity tests on the full sample. Those tests, however, are instructed to detect only mixtures with sufficiently high probability (weight) and disregard low-density mixtures (which are unlikely to be preserved in the high-quantile tail of the sample) as they would prevent any form of stationarity. Nonetheless, low-density mixture distributions can persist and even exacerbate in the tail, and, when not considered, they can impair pWCET estimation in EVT-based approaches, leading to overly pessimistic or optimistic bounds. In this work, we propose TailID, an iterative point-wise approach that builds on the asymptotic convergence of the Maximum Likelihood Estimator (MLE) of the Extreme Value Index (EVI) parameter ξ to detect low-density mixture distributions on high-quantile tails and use this information to steer EVT tail selection. The benefits of the proposed method are assessed on synthetic mixture distributions and real data collected on an industrially representative embedded platform.

Cite as

Blau Manau, Sergi Vilardell, Isabel Serra, Enrico Mezzetti, Jaume Abella, and Francisco J. Cazorla. Detecting Low-Density Mixtures in High-Quantile Tails for pWCET Estimation. In 37th Euromicro Conference on Real-Time Systems (ECRTS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 335, pp. 20:1-20:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{manau_et_al:LIPIcs.ECRTS.2025.20,
  author =	{Manau, Blau and Vilardell, Sergi and Serra, Isabel and Mezzetti, Enrico and Abella, Jaume and Cazorla, Francisco J.},
  title =	{{Detecting Low-Density Mixtures in High-Quantile Tails for pWCET Estimation}},
  booktitle =	{37th Euromicro Conference on Real-Time Systems (ECRTS 2025)},
  pages =	{20:1--20:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-377-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{335},
  editor =	{Mancuso, Renato},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2025.20},
  URN =		{urn:nbn:de:0030-drops-235982},
  doi =		{10.4230/LIPIcs.ECRTS.2025.20},
  annote =	{Keywords: WCET, EVT}
}
Document
Per-Flow Performance Guarantees in Networked Systems with Complex Feedback Structures

Authors: Anja Hamscher, Lukas Wildberger, and Jens Schmitt

Published in: LIPIcs, Volume 335, 37th Euromicro Conference on Real-Time Systems (ECRTS 2025)


Abstract
Many modern networked real-time systems encompass complex feedback structures and require stringent timing guarantees, especially bounds on the network delay. Network Calculus (NC) is a versatile methodology to compute such performance guarantees per individual flow; in particular, some fundamental results on how to deal with feedback exist. Yet, these are restricted to simple feedback structures and are mostly constrained to an analysis at the aggregate level (not per flow). In our work, we analyze more complex feedback structures than previously investigated by reducing them to canonical structures. We transform these closed-loop systems (with feedback) into open-loop systems (without feedback) and, subsequently, perform a per-flow analysis exploiting very recent NC results on per-flow performance guarantees. In a numerical experiment, we compare our new method to the current state-of-the-art which only allows for an aggregate FIFO analysis. We also compute how feedback constraints need to be allocated to ensure that a feedback system provides the same service as the system without feedback, in a sense providing for an optimal control. Furthermore, we compare different allocation strategies under a fixed budget for the feedback constraints.

Cite as

Anja Hamscher, Lukas Wildberger, and Jens Schmitt. Per-Flow Performance Guarantees in Networked Systems with Complex Feedback Structures. In 37th Euromicro Conference on Real-Time Systems (ECRTS 2025). Leibniz International Proceedings in Informatics (LIPIcs), Volume 335, pp. 18:1-18:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{hamscher_et_al:LIPIcs.ECRTS.2025.18,
  author =	{Hamscher, Anja and Wildberger, Lukas and Schmitt, Jens},
  title =	{{Per-Flow Performance Guarantees in Networked Systems with Complex Feedback Structures}},
  booktitle =	{37th Euromicro Conference on Real-Time Systems (ECRTS 2025)},
  pages =	{18:1--18:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-377-5},
  ISSN =	{1868-8969},
  year =	{2025},
  volume =	{335},
  editor =	{Mancuso, Renato},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2025.18},
  URN =		{urn:nbn:de:0030-drops-235961},
  doi =		{10.4230/LIPIcs.ECRTS.2025.18},
  annote =	{Keywords: Real-Time Networks, Network Calculus, Feedback Control}
}
Document
SP-IMPact: A Framework for Static Partitioning Interference Mitigation and Performance Analysis

Authors: Diogo Costa, Gonçalo Moreira, Afonso Oliveira, José Martins, and Sandro Pinto

Published in: OASIcs, Volume 128, Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)


Abstract
Modern embedded systems are evolving toward complex, heterogeneous architectures to accommodate increasingly demanding applications. Driven by industry SWAP-C (Size, Weight, Power, and Cost) constraints, this shift has led to the consolidation of multiple systems onto single hardware platforms. Static Partitioning Hypervisors (SPHs) offer a promising solution to partition hardware resources and provide spatial isolation between critical workloads. However, shared hardware resources like the Last-Level Cache (LLC) and system bus can introduce significant temporal interference between virtual machines (VMs), negatively impacting performance and predictability. Over the past decade, academia and industry have focused on developing interference mitigation techniques, such as cache partitioning and memory bandwidth reservation. Configuring these techniques, however, is complex and time-consuming. Cache partitioning requires careful balancing of cache sections across VMs, while memory bandwidth reservation requires tuning bandwidth budgets and periods. With numerous possible configurations, testing all combinations is impractical and often leads to suboptimal configurations. Moreover, there is a gap in understanding how these techniques interact, as their combined use can result in compounded or conflicting effects on system performance. Static analysis solutions that estimate worst-case execution times (WCET) and upper bounds on execution times provide some guidance for configuring interference mitigation techniques. While useful in identifying potential interference effects, these tools often fail to capture the full complexity of modern multi-core systems, as they typically focus on a limited set of shared resources and neglect other sources of contention, such as IOMMUs and interrupt controllers. To address these challenges, we introduce SP-IMPact, an open-source framework designed to analyze and guide the configuration of interference mitigation techniques, through the deployment of diverse VM configurations and setups, and assessment of hardware-level contention (leveraging SPHs). It supports two mitigation techniques: (i) cache coloring and (ii) memory bandwidth reservation, while also evaluating the interactions between these techniques and their cumulative impact on system performance. By providing insights on real hardware platforms, SP-IMPact helps to optimize the configuration of these techniques in mixed-criticality systems, ensuring both performance and predictability.

Cite as

Diogo Costa, Gonçalo Moreira, Afonso Oliveira, José Martins, and Sandro Pinto. SP-IMPact: A Framework for Static Partitioning Interference Mitigation and Performance Analysis. In Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025). Open Access Series in Informatics (OASIcs), Volume 128, pp. 5:1-5:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{costa_et_al:OASIcs.NG-RES.2025.5,
  author =	{Costa, Diogo and Moreira, Gon\c{c}alo and Oliveira, Afonso and Martins, Jos\'{e} and Pinto, Sandro},
  title =	{{SP-IMPact: A Framework for Static Partitioning Interference Mitigation and Performance Analysis}},
  booktitle =	{Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)},
  pages =	{5:1--5:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-366-9},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{128},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2025.5},
  URN =		{urn:nbn:de:0030-drops-229911},
  doi =		{10.4230/OASIcs.NG-RES.2025.5},
  annote =	{Keywords: Virtualization, Contention, Multi-core Interference, Mixed-Criticality Systems, Arm}
}
Document
H-MBR: Hypervisor-Level Memory Bandwidth Reservation for Mixed Criticality Systems

Authors: Afonso Oliveira, Diogo Costa, Gonçalo Moreira, José Martins, and Sandro Pinto

Published in: OASIcs, Volume 128, Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)


Abstract
Recent advancements in fields such as automotive and aerospace have driven a growing demand for robust computational resources. Applications that were once designed for basic Microcontroller Units (MCUs) are now deployed on highly heterogeneous System-on-Chip (SoC) platforms. While these platforms deliver the necessary computational performance, they also present challenges related to resource sharing and predictability. These challenges are particularly pronounced when consolidating safety-critical and non-safety-critical systems, the so-called Mixed-Criticality Systems (MCS) to adhere to strict Size, Weight, Power, and Cost (SWaP-C) requirements. MCS consolidation on shared platforms requires stringent spatial and temporal isolation to comply with functional safety standards (e.g., ISO 26262). Virtualization, mainly leveraged by hypervisors, is a key technology that ensures spatial isolation across multiple OSes and applications; however ensuring temporal isolation remains challenging due to contention on shared resources, such as main memory, caches, and system buses, which impacts real-time performance and predictability. To mitigate this problem, several strategies (e.g., cache coloring and memory bandwidth reservation) have been proposed. Although cache coloring is typically implemented on state-of-the-art hypervisors, memory bandwidth reservation approaches are commonly implemented at the Linux kernel level or rely on dedicated hardware and typically do not consider the concept of Virtual Machines that can run different OSes. To fill the gap between current memory bandwidth reservation solutions and the deployment of MCSs that operate on a hypervisor, this work introduces H-MBR, an open-source VM-centric memory bandwidth reservation mechanism. H-MBR features (i) VM-centric bandwidth reservation, (ii) OS and platform agnosticism, and (iii) reduced overhead. Empirical results evidenced no overhead on non-regulated workloads, and negligible overhead (<1%) for regulated workloads for regulation periods of 2 µs or higher.

Cite as

Afonso Oliveira, Diogo Costa, Gonçalo Moreira, José Martins, and Sandro Pinto. H-MBR: Hypervisor-Level Memory Bandwidth Reservation for Mixed Criticality Systems. In Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025). Open Access Series in Informatics (OASIcs), Volume 128, pp. 4:1-4:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{oliveira_et_al:OASIcs.NG-RES.2025.4,
  author =	{Oliveira, Afonso and Costa, Diogo and Moreira, Gon\c{c}alo and Martins, Jos\'{e} and Pinto, Sandro},
  title =	{{H-MBR: Hypervisor-Level Memory Bandwidth Reservation for Mixed Criticality Systems}},
  booktitle =	{Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)},
  pages =	{4:1--4:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-366-9},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{128},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2025.4},
  URN =		{urn:nbn:de:0030-drops-229905},
  doi =		{10.4230/OASIcs.NG-RES.2025.4},
  annote =	{Keywords: Virtualization, Multi-core Interference, Mixed-Criticality Systems, Arm, Memory Bandwidth Reservation}
}
Document
Low-Latency Real-Time Applications on Heterogeneous MPSoCs

Authors: Nicolas Coppik, Pascal Becker, and Marcus Ritter

Published in: OASIcs, Volume 128, Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)


Abstract
Heterogeneous Multi-Processor Systems-on-Chip (MPSoCs) that combine multiple, heterogeneous processing units are becoming increasingly popular for a wide range of applications, including industrial applications, where complex real-time applications can benefit from the performance and flexibility they offer. However, deploying real-time applications with low latency requirements across multiple processing units on such MPSoCs remains a challenging problem, particularly when communication between processors is required on a time-critical path. Existing solutions generally rely on the presence of at least one full-featured, general-purpose operating system on the device, and do not cater to the requirements of distributed, low-latency real-time applications. In this paper, we investigate the performance, with a focus on latency, of different options for communication between CPUs, including inter-processor interrupts and shared memory communication via different memories, on the popular Xilinx Zynq UltraScale+ platform and propose a novel solution for communication between heterogeneous processing units that relies only on the availability of shared memory. Our solution is capable of achieving sub-microsecond latencies for signaling and the transfer of small amounts of data between processing units, making it suitable for deploying distributed, low-latency real-time applications.

Cite as

Nicolas Coppik, Pascal Becker, and Marcus Ritter. Low-Latency Real-Time Applications on Heterogeneous MPSoCs. In Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025). Open Access Series in Informatics (OASIcs), Volume 128, pp. 2:1-2:14, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{coppik_et_al:OASIcs.NG-RES.2025.2,
  author =	{Coppik, Nicolas and Becker, Pascal and Ritter, Marcus},
  title =	{{Low-Latency Real-Time Applications on Heterogeneous MPSoCs}},
  booktitle =	{Sixth Workshop on Next Generation Real-Time Embedded Systems (NG-RES 2025)},
  pages =	{2:1--2:14},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-366-9},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{128},
  editor =	{Yomsi, Patrick Meumeu and Wildermann, Stefan},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.NG-RES.2025.2},
  URN =		{urn:nbn:de:0030-drops-229883},
  doi =		{10.4230/OASIcs.NG-RES.2025.2},
  annote =	{Keywords: real-time systems, heterogeneous systems, latency, inter-core communication}
}
Document
Towards Studying the Effect of Compiler Optimizations and Software Randomization on GPU Reliability

Authors: Pau López Castillón, Xavier Caricchio Hernández, and Leonidas Kosmidis

Published in: OASIcs, Volume 127, 16th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 14th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2025)


Abstract
The evolution of Graphics Processing Unit (GPU) compilers has facilitated the support for general-purpose programming languages across various architectures. The NVIDIA CUDA Compiler (NVCC) employs multiple compilation levels prior to generating machine code, implementing intricate optimizations to enhance performance. These optimizations influence the manner in which software is mapped to the underlying hardware, which can also impact GPU reliability. TASA is a source-to-source code randomization tool designed to alter the mapping of software onto the underlying hardware. It achieves this by generating random permutations of variable and function declarations, thereby introducing random padding between declarations of different types and modifying the program memory layout. Since this modifies their location in the memory, it also modifies their cache placement, affecting both their execution time (due to the different conflicts between them, which result in a different amount of cache misses in every execution), as well as their lifetime in the cache. In this work, which is part of the HiPEAC Student Challenge 2025, we first examine the reproducibility of a subset of data presented in the ACM TACO paper "Assessing the Impact of Compiler Optimizations on GPU Reliability" [Santos et al., 2024], and second we extend it by combining it with our proposal of software randomization. The paper indicates that the -O3 optimization flag facilitates an increased workload before failures occur within the application. By employing TASA, we investigate the impact of GPU randomization on reliability and performance metrics. By reproducing the results of the paper on a different GPU platform, we observe the same trend as reported in the original publication. Moreover, our preliminary results with the application of software randomization show in several cases an improved Mean Waiting Before Failure (MWBF) compared to the original source code.

Cite as

Pau López Castillón, Xavier Caricchio Hernández, and Leonidas Kosmidis. Towards Studying the Effect of Compiler Optimizations and Software Randomization on GPU Reliability. In 16th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 14th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2025). Open Access Series in Informatics (OASIcs), Volume 127, pp. 4:1-4:10, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{castillon_et_al:OASIcs.PARMA-DITAM.2025.4,
  author =	{Castill\'{o}n, Pau L\'{o}pez and Hern\'{a}ndez, Xavier Caricchio and Kosmidis, Leonidas},
  title =	{{Towards Studying the Effect of Compiler Optimizations and Software Randomization on GPU Reliability}},
  booktitle =	{16th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 14th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2025)},
  pages =	{4:1--4:10},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-363-8},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{127},
  editor =	{Cattaneo, Daniele and Fazio, Maria and Kosmidis, Leonidas and Morabito, Gabriele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.PARMA-DITAM.2025.4},
  URN =		{urn:nbn:de:0030-drops-229083},
  doi =		{10.4230/OASIcs.PARMA-DITAM.2025.4},
  annote =	{Keywords: Graphics processing units, reliability, software randomization, error rate}
}
Document
Analysis of GPU Memory Allocation Characteristics

Authors: Marcos Rodriguez, Irune Yarza, Leonidas Kosmidis, and Alejandro J. Calderón

Published in: OASIcs, Volume 127, 16th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 14th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2025)


Abstract
The number of applications subject to safety-critical regulations is on the rise, and consequently, the computing requirements for such applications are increasing as well. This trend has led to the integration of General-Purpose Graphics Processing Units (GPGPUs) into these systems. However, the inherent characteristics of GPGPUs, including their black-box nature, dynamic allocation mechanisms, and frequent use of pointers, present challenges in certifying these applications for safety-critical systems. This paper aims to shed light on the unique characteristics of GPU programs and how they impact the certification process. To achieve this goal, several allocation methods are rigorously evaluated to determine which one is best suited to an application, regarding the program characteristics within the safety-critical domain. By conducting this evaluation, we seek to provide insights into the complexities of GPU memory accesses and its compatibility with safety-critical requirements. The ultimate objective is to offer recommendations on the most appropriate allocation method based on the unique needs of each application, thus contributing to the safe and reliable integration of GPGPUs into safety-critical systems.

Cite as

Marcos Rodriguez, Irune Yarza, Leonidas Kosmidis, and Alejandro J. Calderón. Analysis of GPU Memory Allocation Characteristics. In 16th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 14th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2025). Open Access Series in Informatics (OASIcs), Volume 127, pp. 1:1-1:15, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2025)


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@InProceedings{rodriguez_et_al:OASIcs.PARMA-DITAM.2025.1,
  author =	{Rodriguez, Marcos and Yarza, Irune and Kosmidis, Leonidas and Calder\'{o}n, Alejandro J.},
  title =	{{Analysis of GPU Memory Allocation Characteristics}},
  booktitle =	{16th Workshop on Parallel Programming and Run-Time Management Techniques for Many-Core Architectures and 14th Workshop on Design Tools and Architectures for Multicore Embedded Computing Platforms (PARMA-DITAM 2025)},
  pages =	{1:1--1:15},
  series =	{Open Access Series in Informatics (OASIcs)},
  ISBN =	{978-3-95977-363-8},
  ISSN =	{2190-6807},
  year =	{2025},
  volume =	{127},
  editor =	{Cattaneo, Daniele and Fazio, Maria and Kosmidis, Leonidas and Morabito, Gabriele},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/OASIcs.PARMA-DITAM.2025.1},
  URN =		{urn:nbn:de:0030-drops-229057},
  doi =		{10.4230/OASIcs.PARMA-DITAM.2025.1},
  annote =	{Keywords: CUDA, Memory allocation, Rodinia, Embedded}
}
Document
Quasi Isolation QoS Setups to Control MPSoC Contention in Integrated Software Architectures

Authors: Sergio Garcia-Esteban, Alejandro Serrano-Cases, Jaume Abella, Enrico Mezzetti, and Francisco J. Cazorla

Published in: LIPIcs, Volume 262, 35th Euromicro Conference on Real-Time Systems (ECRTS 2023)


Abstract
The use of integrated architectures, such as integrated modular avionics (IMA) in avionics, IMA-SP in space, and AUTOSAR in automotive, running on Multi-Processor System-on-Chip (MPSoC) is on the rise. Timing isolation among the different software partitions or applications thereof in an integrated architecture is key to simplifying software integration and its timing validation by ensuring the performance of each partition has no or very limited impact on others despite they share MPSoC’s hardware resources. In this work, we contend that the increasing hardware support for Quality of Service (QoS) guarantees in modern MPSoCs can be leveraged via specific setups to provide strong, albeit not full, isolation among different software partitions. We introduce the concept of Quasi Isolation QoS (QIQoS) setups and instantiate it in the Xilinx Zynq UltraScale+. To that end, out of the millions of setups offered by the different QoS mechanisms, we identify specific QoS configurations that isolate the traffic of time-critical software partitions executing in the core cluster from that generated by contender partitions in the programmable logic. Our results show that the selected isolation setup results in performance variations of the partitions run in the computing cores that are below 6 percentage points, even under scenarios with extremely high traffic coming from the programmable logic.

Cite as

Sergio Garcia-Esteban, Alejandro Serrano-Cases, Jaume Abella, Enrico Mezzetti, and Francisco J. Cazorla. Quasi Isolation QoS Setups to Control MPSoC Contention in Integrated Software Architectures. In 35th Euromicro Conference on Real-Time Systems (ECRTS 2023). Leibniz International Proceedings in Informatics (LIPIcs), Volume 262, pp. 5:1-5:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2023)


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@InProceedings{garciaesteban_et_al:LIPIcs.ECRTS.2023.5,
  author =	{Garcia-Esteban, Sergio and Serrano-Cases, Alejandro and Abella, Jaume and Mezzetti, Enrico and Cazorla, Francisco J.},
  title =	{{Quasi Isolation QoS Setups to Control MPSoC Contention in Integrated Software Architectures}},
  booktitle =	{35th Euromicro Conference on Real-Time Systems (ECRTS 2023)},
  pages =	{5:1--5:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-280-8},
  ISSN =	{1868-8969},
  year =	{2023},
  volume =	{262},
  editor =	{Papadopoulos, Alessandro V.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2023.5},
  URN =		{urn:nbn:de:0030-drops-180346},
  doi =		{10.4230/LIPIcs.ECRTS.2023.5},
  annote =	{Keywords: Multicore, Interference, QoS}
}
Document
Using Quantile Regression in Neural Networks for Contention Prediction in Multicore Processors

Authors: Axel Brando, Isabel Serra, Enrico Mezzetti, Jaume Abella, and Francisco J. Cazorla

Published in: LIPIcs, Volume 231, 34th Euromicro Conference on Real-Time Systems (ECRTS 2022)


Abstract
The development of multicore-based embedded real-time systems is a complex process that encompasses several phases. During the software design and development phases (DDP), and prior to the validation phase, key decisions are taken that cover several aspects of the system under development, from hardware selection and configuration, to the identification and mapping of software functions to the processing nodes. The timing dimension steers a large fraction of those decisions as the correctness of the final system ultimately depends on the implemented functions being able to execute within the allotted time budgets. Early execution time figures already in the DDP are thus needed to prevent flawed design decisions resulting in timing misbehavior being intercepted at the timing analysis step in the advanced development phases, when rolling back to different design decisions is extremely onerous. Multicore timing interference compounds this situation as it has been shown to largely impact execution time of tasks and, therefore, must be factored in when deriving early timing bounds. To effectively prevent misconfigurations while preserving resource efficiency, early timing estimates, typically derived from previous projects or early versions of the software functions, should conservatively and tightly overestimate the timing requirements of the final system configuration including multicore contention. In this work, we show that multi-linear regression (MLR) models and neural network (NN) models can be used to predict the impact of multicore contention on tasks' execution time and hence, derive contention-aware early time budgets, as soon as a release (binary) of the application is available. However, those techniques widely used in the mainstream domain minimize the average/mean case and the predicted impact of contention frequently underestimates the impact that can potentially arise at run time. In order to cover this gap, we propose the use of quantile regression neural networks (QRNN), which are specifically designed to predict the desired high quantile. QRNN reduces the number of underestimations compared to MLR and NN models while containing the overestimation by preserving the high quality prediction. For a set of workloads composed by representative kernels running on a NXP T2080 processor, QRNN reduces the number of underestimations to 8.8% compared to 46.8% and 31.3% for MLR and NN models respectively, while keeping the average over estimation in 1%. QRNN exposes a parameter, the target quantile, that allows controlling the behavior of the predictions so it adapts to user’s needs.

Cite as

Axel Brando, Isabel Serra, Enrico Mezzetti, Jaume Abella, and Francisco J. Cazorla. Using Quantile Regression in Neural Networks for Contention Prediction in Multicore Processors. In 34th Euromicro Conference on Real-Time Systems (ECRTS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 231, pp. 4:1-4:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{brando_et_al:LIPIcs.ECRTS.2022.4,
  author =	{Brando, Axel and Serra, Isabel and Mezzetti, Enrico and Abella, Jaume and Cazorla, Francisco J.},
  title =	{{Using Quantile Regression in Neural Networks for Contention Prediction in Multicore Processors}},
  booktitle =	{34th Euromicro Conference on Real-Time Systems (ECRTS 2022)},
  pages =	{4:1--4:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-239-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{231},
  editor =	{Maggio, Martina},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2022.4},
  URN =		{urn:nbn:de:0030-drops-163213},
  doi =		{10.4230/LIPIcs.ECRTS.2022.4},
  annote =	{Keywords: Neural Networks, Quantile Prediction, Multicore Contention}
}
Document
Using Markov’s Inequality with Power-Of-k Function for Probabilistic WCET Estimation

Authors: Sergi Vilardell, Isabel Serra, Enrico Mezzetti, Jaume Abella, Francisco J. Cazorla, and Joan del Castillo

Published in: LIPIcs, Volume 231, 34th Euromicro Conference on Real-Time Systems (ECRTS 2022)


Abstract
Deriving WCET estimates for software programs with probabilistic means (a.k.a. pWCET estimation) has received significant attention during last years as a way to deal with the increased complexity of the processors used in real-time systems. Many works build on Extreme Value Theory (EVT) that is fed with a sample of the collected data (execution times). In its application, EVT carries two sources of uncertainty: the first one that is intrinsic to the EVT model and relates to determining the subset of the sample that belongs to the (upper) tail, and hence, is actually used by EVT for prediction; and the second one that is induced by the sampling process and hence is inherent to all sample-based methods. In this work, we show that Markov’s inequality can be used to obtain provable trustworthy probabilistic bounds to the tail of a distribution without incurring any model-intrinsic uncertainty. Yet, it produces pessimistic estimates that we shave substantially by proposing the use of a power-of-k function instead of the default identity function used by Markov’s inequality. Lastly, we propose a method to deal with sampling uncertainty for Markov’s inequality that consistently improves EVT estimates on synthetic and real data obtained from a railway application.

Cite as

Sergi Vilardell, Isabel Serra, Enrico Mezzetti, Jaume Abella, Francisco J. Cazorla, and Joan del Castillo. Using Markov’s Inequality with Power-Of-k Function for Probabilistic WCET Estimation. In 34th Euromicro Conference on Real-Time Systems (ECRTS 2022). Leibniz International Proceedings in Informatics (LIPIcs), Volume 231, pp. 20:1-20:24, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2022)


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@InProceedings{vilardell_et_al:LIPIcs.ECRTS.2022.20,
  author =	{Vilardell, Sergi and Serra, Isabel and Mezzetti, Enrico and Abella, Jaume and Cazorla, Francisco J. and del Castillo, Joan},
  title =	{{Using Markov’s Inequality with Power-Of-k Function for Probabilistic WCET Estimation}},
  booktitle =	{34th Euromicro Conference on Real-Time Systems (ECRTS 2022)},
  pages =	{20:1--20:24},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-239-6},
  ISSN =	{1868-8969},
  year =	{2022},
  volume =	{231},
  editor =	{Maggio, Martina},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2022.20},
  URN =		{urn:nbn:de:0030-drops-163377},
  doi =		{10.4230/LIPIcs.ECRTS.2022.20},
  annote =	{Keywords: Markov’s inequality, probabilistic time estimates, probabilistic WCET, Extreme Value Theory}
}
Document
Leveraging Hardware QoS to Control Contention in the Xilinx Zynq UltraScale+ MPSoC

Authors: Alejandro Serrano-Cases, Juan M. Reina, Jaume Abella, Enrico Mezzetti, and Francisco J. Cazorla

Published in: LIPIcs, Volume 196, 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)


Abstract
The interference co-running tasks generate on each other’s timing behavior continues to be one of the main challenges to be addressed before Multi-Processor System-on-Chip (MPSoCs) are fully embraced in critical systems like those deployed in avionics and automotive domains. Modern MPSoCs like the Xilinx Zynq UltraScale+ incorporate hardware Quality of Service (QoS) mechanisms that can help controlling contention among tasks. Given the distributed nature of modern MPSoCs, the route a request follows from its source (usually a compute element like a CPU) to its target (usually a memory) crosses several QoS points, each one potentially implementing a different QoS mechanism. Mastering QoS mechanisms individually, as well as their combined operation, is pivotal to obtain the expected benefits from the QoS support. In this work, we perform, to our knowledge, the first qualitative and quantitative analysis of the distributed QoS mechanisms in the Xilinx UltraScale+ MPSoC. We empirically derive QoS information not covered by the technical documentation, and show limitations and benefits of the available QoS support. To that end, we use a case study building on neural network kernels commonly used in autonomous systems in different real-time domains.

Cite as

Alejandro Serrano-Cases, Juan M. Reina, Jaume Abella, Enrico Mezzetti, and Francisco J. Cazorla. Leveraging Hardware QoS to Control Contention in the Xilinx Zynq UltraScale+ MPSoC. In 33rd Euromicro Conference on Real-Time Systems (ECRTS 2021). Leibniz International Proceedings in Informatics (LIPIcs), Volume 196, pp. 3:1-3:26, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2021)


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@InProceedings{serranocases_et_al:LIPIcs.ECRTS.2021.3,
  author =	{Serrano-Cases, Alejandro and Reina, Juan M. and Abella, Jaume and Mezzetti, Enrico and Cazorla, Francisco J.},
  title =	{{Leveraging Hardware QoS to Control Contention in the Xilinx Zynq UltraScale+ MPSoC}},
  booktitle =	{33rd Euromicro Conference on Real-Time Systems (ECRTS 2021)},
  pages =	{3:1--3:26},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-192-4},
  ISSN =	{1868-8969},
  year =	{2021},
  volume =	{196},
  editor =	{Brandenburg, Bj\"{o}rn B.},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2021.3},
  URN =		{urn:nbn:de:0030-drops-139340},
  doi =		{10.4230/LIPIcs.ECRTS.2021.3},
  annote =	{Keywords: Quality of Service, Real-Time Systems, MPSoC, Multicore Contention}
}
Document
Tracing Hardware Monitors in the GR712RC Multicore Platform: Challenges and Lessons Learnt from a Space Case Study

Authors: Xavier Palomo, Mikel Fernandez, Sylvain Girbal, Enrico Mezzetti, Jaume Abella, Francisco J. Cazorla, and Laurent Rioux

Published in: LIPIcs, Volume 165, 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)


Abstract
The demand for increased computing performance is driving industry in critical-embedded systems (CES) domains, e.g. space, towards the use of multicores processors. Multicores, however, pose several challenges that must be addressed before their safe adoption in critical embedded domains. One of the prominent challenges is software timing analysis, a fundamental step in the verification and validation process. Monitoring and profiling solutions, traditionally used for debugging and optimization, are increasingly exploited for software timing in multicores. In particular, hardware event monitors related to requests to shared hardware resources are building block to assess and restraining multicore interference. Modern timing analysis techniques build on event monitors to track and control the contention tasks can generate each other in a multicore platform. In this paper we look into the hardware profiling problem from an industrial perspective and address both methodological and practical problems when monitoring a multicore application. We assess pros and cons of several profiling and tracing solutions, showing that several aspects need to be taken into account while considering the appropriate mechanism to collect and extract the profiling information from a multicore COTS platform. We address the profiling problem on a representative COTS platform for the aerospace domain to find that the availability of directly-accessible hardware counters is not a given, and it may be necessary to the develop specific tools that capture the needs of both the user’s and the timing analysis technique requirements. We report challenges in developing an event monitor tracing tool that works for bare-metal and RTEMS configurations and show the accuracy of the developed tool-set in profiling a real aerospace application. We also show how the profiling tools can be exploited, together with handcrafted benchmarks, to characterize the application behavior in terms of multicore timing interference.

Cite as

Xavier Palomo, Mikel Fernandez, Sylvain Girbal, Enrico Mezzetti, Jaume Abella, Francisco J. Cazorla, and Laurent Rioux. Tracing Hardware Monitors in the GR712RC Multicore Platform: Challenges and Lessons Learnt from a Space Case Study. In 32nd Euromicro Conference on Real-Time Systems (ECRTS 2020). Leibniz International Proceedings in Informatics (LIPIcs), Volume 165, pp. 15:1-15:25, Schloss Dagstuhl – Leibniz-Zentrum für Informatik (2020)


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@InProceedings{palomo_et_al:LIPIcs.ECRTS.2020.15,
  author =	{Palomo, Xavier and Fernandez, Mikel and Girbal, Sylvain and Mezzetti, Enrico and Abella, Jaume and Cazorla, Francisco J. and Rioux, Laurent},
  title =	{{Tracing Hardware Monitors in the GR712RC Multicore Platform: Challenges and Lessons Learnt from a Space Case Study}},
  booktitle =	{32nd Euromicro Conference on Real-Time Systems (ECRTS 2020)},
  pages =	{15:1--15:25},
  series =	{Leibniz International Proceedings in Informatics (LIPIcs)},
  ISBN =	{978-3-95977-152-8},
  ISSN =	{1868-8969},
  year =	{2020},
  volume =	{165},
  editor =	{V\"{o}lp, Marcus},
  publisher =	{Schloss Dagstuhl -- Leibniz-Zentrum f{\"u}r Informatik},
  address =	{Dagstuhl, Germany},
  URL =		{https://drops.dagstuhl.de/entities/document/10.4230/LIPIcs.ECRTS.2020.15},
  URN =		{urn:nbn:de:0030-drops-123787},
  doi =		{10.4230/LIPIcs.ECRTS.2020.15},
  annote =	{Keywords: Multicore Contention, Timing interference, Hardware Event Counters, PMC}
}
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