AA

Dr.-Ing. Ayesha Afzal

Erlangen National High-Performance Computing Center (NHR@FAU)

Research associates

Address

Martensstraße 1 91058 Erlangen
Room: 01.033, Floor: 01

Contact

Social Media and Websites

Office Hours

By appointment (via email)

Short Bio

Ayesha Afzal is a researcher at the Erlangen National High Performance Computing Center (NHR@FAU) in Germany. She holds a PhD in Computer Science, an MSc in Computational Engineering, and a BSc in Electrical Engineering. Her PhD research, titled “A Holistic White-Box Approach to Performance Modeling for Supercomputing,” was conducted under the supervision of Prof. Dr. Gerhard Wellein and focused on analytical performance models, performance tools, and parallel simulation frameworks in HPC. She also explores multi-core architectures, parallel algorithms and programming models, domain-specific languages, energy efficiency, operational cost management, and sustainable computing, while teaching tutorials and supervising undergraduate and master’s students. She is actively involved in HPC initiatives such as KONWHIR with the Leibniz Supercomputing Centre (LRZ), the DFG-funded MOD4COMP project with TU Dresden and Jülich, and the NHR EEC project across German NHR centers.

Ayesha contributes to the HPC community through various leadership roles. Within the IEEE Computer Society, she serves as Vice Chair of both the Germany Section Chapter and Region 8 Area 2, and as Secretary of IEEE TCHPC. She founded the NHR Women in HPC chapter, is elected women’s representative at FAU, and organizes recurring workshops at major international conferences (SC, ISC, ACM HPDC, and SCA/HPCAsia). She is a member of several professional societies (IEEE, ACM, SIAM, and PRACE) and actively contributes to the scientific community as a chair, vice chair, committee member, journal reviewer, panelist, and speaker. She was featured in the Top 100 Future Leaders Role Model List (2022–2025), supported by Yahoo Finance and YouTube, won WeAreTheCity’s Global Award for Achievement (2023) and was listed in the SCW75 HPC list (2026). She has authored numerous peer-reviewed publications, and her work has received several distinctions, including the ISC PhD Forum Award (1st place, 2021), IEEE TPDS Best Paper Runner-up Award (2023), SC PMBS Best Short Paper Award (2023), SC Best Research Poster Finalist (2024), ISC Best Research Poster Award (1st place, 2025) and PhD with highest distinction (summa cum laude, 2026).

  • May 2024 – Present: Founder and Lead – NHR Women in HPC (WHPC) Chapter
  • May 2024 – Jan 2028: Vice Chair – IEEE Computer Society Germany Section Chapter C016 (elected twice)
  • Jan 2025 – Jan 2027: Vice Chair – IEEE Computer Society Region 8 Area 2 (Benelux, Denmark, France, Germany, Portugal, Spain, UK & Ireland, Switzerland; appointed twice)
  • April 2026 – April 2028: Secretary – IEEE Computer Society Technical Community on High Performance Computing (TCHPC)
  • Apr 2026 – Apr 2028: Elected Women's representative – Department of Computer Science, FAU Erlangen Nürnberg
  • Apr 2024 – Apr 2025: Lead – IEEEXtreme Region 8 Germany Section
  • 2026: General Chair – 3rd International Workshop on Energy Efficiency with Sustainable Performance (EESP) at 38th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Chicago, IL, USA
  • 2026: General Chair – 1st International Workshop on Rising Innovators in Sustainable Exacomputing (RISE) at 38th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Chicago, IL, USA
  • 2026: General Chair – 2nd International Workshop on Energy Efficiency with Sustainable Performance (EESP) at 41th ISC High Performance, Hamburg, Germany
  • 2026: Co-Chair – 6th International Workshop on Energy Efficient High Performance Computing Systems (EE HPC SOP) at SCA/HPCAsia, Osaka, Japan
  • 2026: Co-Chair – 16th International Workshop on Energy Efficient High Performance Computing Working Group (EE HPC WG), Online  
  • 2026: Co-Chair – 1st International Birds of a Feather on HPC Procurement, Energy Efficiency and Sustainability at 41st ISC High Performance Conference, Hamburg, Germany
  • 2026: Posters Chair – 38th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Chicago, IL, USA
  • 2026: WHPC Posters Chair – 41st ISC High Performance Conference, Hamburg, Germany
  • 2026: WHPC Program Chair – 32nd International European Conference on Parallel and Distributed Computing (Euro-Par), Pisa, Italy
  • 2026: Publicity Co-Chair – 55th International Conference on Parallel Processing (ICPP), Singapore
  • 2026: Invited Program Session Chair – 41st ISC High Performance Conference, Hamburg, Germany
  • 2025: General Chair – 1st International Workshop on Energy Efficiency with Sustainable Performance (EESP) at 40th ISC High Performance, Hamburg, Germany
  • 2025: General Chair – 5th International Workshop on Performance EngineeRing, Modelling, Analysis, and VisualizatiOn STrategy (PERMAVOST) Workshop at 34th ACM International Symposium on High-Performance Parallel and Distributed Computing (HPDC), Notre Dame, IN, USA
  • 2025: WHPC Posters Chair – 40th ISC High Performance Conference, Hamburg, Germany
  • 2025: WHPC Program Chair – 31st International European Conference on Parallel and Distributed Computing (Euro-Par), Dresden, Germany
  • 2025: Publicity Co-Chair – 54th International Conference on Parallel Processing (ICPP), San Diego, CA, USA
  • 2025: Research Paper Session Chair – 40th ISC High Performance Conference, Hamburg, Germany
  • 2024: Posters Vice Chair – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: Research Posters Vice Chair – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: Doctoral Showcase Vice Chair – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: ACM Student Research Competition Vice Chair – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: Art of HPC Vice Chair – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: Co-Chair – 4th International Workshop on Performance EngineeRing, Modelling, Analysis, and VisualizatiOn STrategy (PERMAVOST) at 33rd ACM International Symposium on High-Performance Parallel and Distributed Computing (HPDC), Pisa, Italy
  • 2024: WHPC Posters Co-Chair – 39th ISC High Performance Conference, Hamburg, Germany
  • 2024: Publicity Chair – 53rd International Conference on Parallel Processing (ICPP), Gotland, Sweden
  • 2023: Co-Chair – 3rd International Workshop on Performance EngineeRing, Modelling, Analysis, and VisualizatiOn STrategy (PERMAVOST) at 32nd ACM International Symposium on High-Performance Parallel and Distributed Computing (HPDC), Orlando, Florida
  • 2023: Mentoring Co-Chair – 19th International Workshop on Women in HPC (WHPC) at 35th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Denver, CO, USA

  • 2026: Technical Papers Committee Member – 26th IEEE International Symposium on Cluster, Cloud and Internet Computing (CCGrid), Sydney, Australia
  • 2026: Technical Papers Committee Member – 40th ACM International Conference on Supercomputing (ICS), Belfast, Northern Ireland, United Kingdom
  • 2026: Technical Papers Committee Member – 16th International Conference on Parallel Processing and Applied Mathematics (PPAM), Poznań, Poland
  • 2026: Technical Papers Committee Member – 6th International Workshop on Performance and Energy Efficiency in Concurrent and Distributed Systems (PECS) at Euro-Par, Pisa, Italy
  • 2026: Technical Papers Committee Member – 6th International Workshop on Energy Efficient HPC State of the Practice (EE HPC SOP) at SCA/HPCAsia, Osaka, Japan
  • 2026: Tech Program Communication Liaison – 38th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Chicago, IL, USA
  • 2026: Student Volunteer Reviewer – 38th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Chicago, IL, USA
  • 2025: Technical Papers Committee Member – 27th IEEE International Conference on Cluster Computing (CLUSTER), Edinburgh, Scotland
  • 2025: Technical Papers Committee Member – 25th IEEE International Symposium on Cluster, Cloud and Internet Computing (CCGrid), Tromsø, Norway
  • 2025: Research Posters Committee Member – 40th ISC High Performance Conference, Hamburg, Germany
  • 2025: WHPC Posters Committee Member – 40th ISC High Performance Conference, Hamburg, Germany
  • 2025: Research/ACM SRC Posters Committee Member – 37th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), St. Louis, MO, USA
  • 2025: Lead Volunteer Reviewer – 37th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), St. Louis, MO, USA
  • 2025: Student Volunteer Reviewer – 37th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), St. Louis, MO, USA
  • 2025: SIGHPC Immersion Reviewer – 37th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), St. Louis, MO, USA
  • 2025: Community Engagement and Support Communication Liaison – 37th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), St. Louis, MO, USA
  • 2024: Technical Papers Committee Member – 26th IEEE International Conference on Cluster Computing (CLUSTER), Kobe, Japan
  • 2024: Technical Papers Committee Member – 30th International European Conference on Parallel and Distributed Computing (Euro-Par) WHPC Session, Madrid, Spain
  • 2024: Research/ACM SRC Posters Committee Member – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: Doctoral Showcase Committee Member – 36th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Atlanta, Georgia, USA
  • 2024: Committee Member – IEEE TechEthics Ad Hoc
  • 2023: Technical Papers Committee Member – 35th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Denver, CO, USA
  • 2023: Technical Papers Committee Member – 25th IEEE International Conference on Cluster Computing (CLUSTER), Santa Fe, New Mexico, USA
  • 2023: Technical Papers Committee Member – 52nd International Conference on Parallel Processing (ICPP), Salt Lake City, Utah, USA
  • 2023: Technical Papers Committee Member – 7th High Performance Computing and Cluster Technologies Conference (HPCCT), Jiaxing, Zhejiang, China
  • 2023: Technical Papers Committee Member – Annual Modeling and Simulation Conference (ANNSIM), Hamilton, ON, Canada
  • 2023: Technical Papers Committee Member – International Workshop on Performance, Portability and Productivity in HPC (P3HPC) at 35th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Denver, CO, USA
  • 2023: Research Posters Committee Member – 35th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Denver, CO, USA
  • 2023: Awards Committee Member – ACM/CSTA Cutler-Bell Prize in High School Computing, Virtual
  • 2023: Awards Committee Member – CSTA CS Teaching Excellence Awards, Virtual
  • 2022: Reviewer – 6th High Performance Computing and Cluster Technologies Conference (HPCCT), Fuzhou, China
  • 2022: Reviewer – CSTA CS Teaching Excellence Award, Chicago, USA
  • 2022: Reviewer – ACM/CSTA Cutler-Bell Prize in High School Computing, Chicago, USA
  • 2022: Reviewer – Annual Conference of Computer Science Teachers Association (CSTA), Chicago, USA
  • 2022: Student Volunteer – 34th IEEE/ACM International Conference for High Performance Computing, Networking, Storage, and Analysis (SC), Denver, CO, USA
  • 2022: Student Volunteer – 9th Annual Platform for Advanced Scientific Computing (PASC) Conference, Basel, Switzerland
  • 2018: Reviewer – 31st International Conference on Architecture of Computing Systems (ARCS), Braunschweig, Germany

Further Publications 2026

  • Afzal A., Hager G., Wellein G.:
    Wattlytics: A Web Platform for Co-Optimizing Performance, Energy, and TCO in HPC Clusters.
    Submitted; ArXiv DIO: 10.48550/arXiv.2604.08182.

2026

2025

2024

2023

2022

2021

2020

2019

2018

2026

  • Afzal A., Hager G., Wellein G.:
    Wattlytics: Peak FLOPS Don’t Buy the Most Science per Euro
    ISC High Performance 2026
    (Hamburg, Germany, 2026-06-22/2026-06-26)
    Download: Poster

2025

2024

2023

  • Afzal A., Hager G., Wellein G.:
    Making Applications Run Faster by Slowing Down Processes?
    ISC High Performance 2023
    (Hamburg, Germany, 2023-05-21/2023-05-25)
    Download: Poster PDF

2022

2021

2019

A Holistic White-Box Approach to Performance Modeling for Supercomputing

An open-access version of the dissertation e-book is available here (PDF, BibTeX).
DOI: 10.25593/978-3-96147-940-5

Abstract

As high-performance computing systems push toward exascale and future zettascale capabilities, their unprecedented architectural complexity, featuring massive core counts, deep memory hierarchies, and heterogeneous components, poses significant challenges to performance modeling. Traditional performance models, often relying on decoupled computation and communication models or additive cost models that assume an idealized bulk synchronous parallel pattern, fail to capture the emergent process overlap dynamics observed in large-scale, distributed-memory programs. Disturbances can trigger large-scale, nonlinear effects that profoundly impact performance. This dissertation introduces a holistic, white-box modeling framework grounded in first principles to capture the coupled effects of noise, bandwidth bottlenecks, code execution, the message passing library, and the network in parallel applications.

The work systematically formulates several fundamental challenges across three interconnected domains: (i) performance modeling, (ii) performance engineering, and (iii) performance simulation and physical modeling. It reveals how localized delays can propagate through inter-process dependencies, amplify system-wide variability, and invalidate additive- or max-based time-to-solution predictions. Through analytical derivations, controlled experiments, and large-scale validation, the work identifies critical performance phenomena, such as idle wave propagation, memory bandwidth-sharing interference, and spontaneous communication-computation overlap, as key drivers of performance variability. These effects arise not from algorithmic flaws but from fundamental hardware–software interactions under shared bottlenecks. These models are validated using both synthetic and real applications, exploring whether noise, traditionally seen as detrimental, can potentially be leveraged for beneficial purposes.

The dissertation develops new analytical models: one that explains desynchronization in scalable programs via idle wave dynamics; another that models bandwidth-sharing among overlapping computational kernels and computation-communication overlap. To support controlled experimentation and reproducible simulation, two novel tools are introduced: DisCostiC, a white-box MPI performance simulator that emulates MPI applications via system-aware skeletons without requiring execution on real hardware; and OsciLite, a Kuramoto-inspired oscillator framework that captures the synchronization dynamics of parallel programs using coupled differential equations.

By combining theoretical insights, simulation, and empirical validation, this dissertation provides a new lens through which the behavior of parallel programs can be understood, predicted, and optimized. Its insights and tools lay the foundation for building performance-aware software, guiding hardware co-design, and redefining performance modeling in the zettascale era.

(excluding paper presentations or poster lighting talks)

  • 2026: Master Thesis – Symon Islam: The Energy Footprint of Generative AI: A Comparative Study of Transformer and State-Space Language Models. (ongoing)
  • 2026: Bachelor Thesis – Markus Manfred Li: Energy Consumption of Modern CPUs and GPUs: A Study with Production Applications (ongoing)
  • 2025: Bachelor Thesis – Onur Karaca: Implementation and Benchmarking of MPI Collectives in a Parallel Simulator Framework
  • 2025: Master Thesis – Jean-Yves Verhaeghe: Exploring Advanced Visualization of MPI-Parallel Programs
  • 2025: Master Thesis – Krishna Sai Lakshmi Gayatri Manda: Performance Analysis of Desynchronization Effects in a Parallel Optical Flow Solver
  • 2024: Master Thesis – Aditya Ujeniya: Extending a Simulation Framework for Performance Assessment of Parallel Applications
  • 2021: Bachelor Thesis – Sebastian Bönning: Integration of Chip-Level Performance Models into a Parallel Simulation Framework
  • 2019: Master Thesis – Hassan Asghar: Development of a Benchmark Suite for Investigating MPI Communication Behavior

Ayesha Afzal holds a Bachelor's degree in Electrical Engineering from the University of Engineering and Technology, Lahore, Pakistan (2012), where she focused on power systems and completed an internship with Siemens' Transformers Energy Division in Lahore. She began her career in teaching, instructing final-year Electrical Engineering courses at the University of Management and Technology, Lahore, before pursuing her Master's degree in Computational Engineering at Friedrich-Alexander-Universität Erlangen-Nürnberg Germany (2015). During her master's, she worked as a Research Assistant at the Department of Regionales Rechenzentrum Erlangen (RRZE) and completed her thesis, “The Cost of Computation: Metrics and Models for Modern Multicore-Based Systems in Scientific Computing,” gaining hands-on experience in high-performance computing systems as well as performance and energy analysis. After parental leave (2015–2017), she joined the Department of Computer Science 12 (Hardware/Software Co-Design) at FAU on the BMFTR-funded HighPerMeshes project, where she designed a domain-specific language and developed target-aware optimization techniques for unstructured grids. Her PhD research, “A Holistic White-Box Approach to Performance Modeling for Supercomputing,” lies at the intersection of analytic performance models, performance tools, and parallel simulation frameworks in HPC. Following maternity leave in 2024, she resumed her researcher position (Wiss. Mitarbeiterin) at the Erlangen National High-Performance Computing Center (NHR@FAU) and is actively involved in HPC initiatives. She has collaborated on research projects with leading international institutions in Japan (University of Tokyo, Kyushu University), Sweden (KTH Royal Institute of Technology), Switzerland (University of Basel), and Germany (NHR centers, LRZ Garching, Paderborn University, ZIB Berlin, Fraunhofer ITWM).

  • English: Professional working proficiency
  • Urdu: Native proficiency
  • Punjabi: Native proficiency
  • German: Elementary proficiency
  • Arabic: Elementary proficiency

  • Jan 2026 – Present: Partnership for Advanced Computing in Europe (PRACE)
  • Oct 2025 – Present: Society for Industrial and Applied Mathematics (SIAM)
  • Oct 2025 – Present: SIAM Activity Group on Supercomputing (SIAG-SC)
  • Oct 2025 – Present: SIAM Activity Group on Computational Science and Engineering (SIAG-CSE)
  • Oct 2023 – Present: Institute of Electrical and Electronics Engineers (IEEE)
  • Oct 2023 – Present: IEEE Computer Society (IEEE CS)
  • Oct 2023 – Present: IEEE Women in Engineering (IEEE-WIE)
  • Oct 2023 – Present: IEEE CS Technical Community on Computer Architecture (IEEE CS TCCA)
  • Oct 2023 – Present: IEEE CS Technical Community on High Performance Computing (IEEE CS TCHPC)
  • Oct 2023 – Present: IEEE CS Technical Community on Parallel Processing (IEEE CS TCPP)
  • Oct 2023 – Present: IEEE CS Technical Community on Distributed Processing (IEEE CS TCDP)
  • Oct 2023 – Present: IEEE CS Technical Community on Data Engineering (IEEE CS TCDE)
  • Oct 2023 – Present: IEEE CS Technical Community on Scalable Computing (IEEE CS TCSC)
  • Oct 2023 – Present: IEEE CS Technical Community on Software Engineering (IEEE CS TCSE)
  • Oct 2023 – Present: IEEE Young Professionals (IEEE YP)
  • Jul 2022 – Present: Association for Computing Machinery (ACM)
  • Jul 2022 – Present: ACM’s Women in Computing (ACM-W)
  • Nov 2021 – Present: Computer Science Teachers Association (CSTA)
  • Aug 2019 – Present: Women in High Performance Computing (WHPC)