Main Interests

My interests revolve around the performance analysis of computer systems. I have published a number of papers on the use of stochastic models for performance analysis of cloud applications, optical networks, and grid computing centers. I am currently part of the MODAClouds research team, working on the design and runtime management of Cloud applications.

I have participated in the development of various tools for performance analysis based on stochastic models. These include LINE, jPhase, Q-MAM, and the SMC-Solver.

Contact Information

Office: Huxley 303
Email: j.perez-bernal AT SYMBOL

Research Projects

MODAClouds: A Model-Driven Approach for the design and execution of applications on multiple Clouds

The main goal of MODAClouds is to provide methods, a decision support system, an open source IDE and run-time environment for the high-level design, early prototyping, semi-automatic code generation, and automatic deployment of applications on multi-Clouds with guaranteed QoS. Visit the MODAClouds website.
Funded by the European Commission.

Past projects
  • Stochastic modeling of optical buffers and switching systems based on Fiber Delay Lines.
    Funded by the FWO-Flanders, Belgium.
  • Greenhouse gas emission abatement curve estimation.
    Funded by the Ministry of Environment, Colombia.


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Recently Accepted

  • Estimating Computational Requirements in Multi-Threaded Applications.
    J.F. Pérez, G. Casale, and S. Pacheco-Sanchez.
    Accepted in IEEE Transactions on Software Engineering.
  • Enhancing Reliability and Response Times via Replication in Computing Clusters.
    Z. Qiu and J.F. Pérez.
    Accepted in INFOCOM 2015.
  • Evaluating the Effectiveness of Replication for Tail-tolerance.
    Z. Qiu and J.F. Pérez.
    Accepted in CCGRID 2015.
  • Planning Distribution Primary Feeders for Smart-Grid Operation via Network Flow Analysis.
    J. L. Morillo, J.F. Pérez, N. Quijano and A. Cadena.
    Accepted in IEEE Power and Energy Systems (PES) General Meeting 2015.


  • Towards a DevOps Approach for Software Quality Engineering.
    J.F. Pérez, W. Wang, and G. Casale.
    Proceesings of WOSP-C (ICPE) 2015.


  • Assessing the impact of concurrent replication with canceling in parallel jobs.
    Z. Qiu and J.F. Pérez.
    Proceedings of IEEE MASCOTS 2014, Paris, France, 2014.
  • Cloud computing: Modeling techniques and their applications.
    D. Ardagna, G. Casale, M. Ciavotta, J.F. Pérez, and W. Wang.
    Journal of Internet Services and Applications, Vol. 5, No. 11, 2014.


  • Dynamic multi-objective planning for distribution systems with distributed generation
    J.L. Morillo, J.F. Pérez, & A. Cadena
    Proceedings of the 4th IEEE/PES Innovative Smart Grid Technologies Europe (ISGT EUROPE), 2013.
  • Assessing SLA compliance from Palladio component models
    J.F. Pérez, & G. Casale
    Proceedings of the 2nd Workshop on Management of resources and services in Cloud and Sky computing (MICAS), IEEE Press, 2013.
  • An Offline Demand Estimation Method for Multi-Threaded Applications
    J.F. Pérez, S. Pacheco-Sanchez & G. Casale
    Proceedings of IEEE MASCOTS 2013.
    Best paper candidate








  • LINE: Efficient Reliability and Performance Analysis of Layered Queueing Models
    J.F. Pérez & G. Casale
    30th Annual UK Performance Engineering Workshop (UKPEW), Newcastle, UK, 2014.
  • Restricted transitions in QBDs, M/G/1- and GI/M/1-type Markov chains
    J.F. Pérez & B. Van Houdt
    15th INFORMS Applied Probability Society Conference, Ithaca, New York, USA, 2009.
  • Benchmarking of Fitting Algorithms for Continuous Phase-Type Distributions
    J.F. Pérez & G. Riaño
    14th INFORMS Applied Probability Society Conference, Eindhoven, The Netherlands, 2007.
  • Medición de eficiencia en el transporte de energía eléctrica. Parte 2: Aplicación de Análisis Envolvente de Datos (Efficiency measurement in electric energy transport. Part 2: Data Envelopment Analysis)
    F. G. Palacios, J. F. Pérez, D. Parra, C. Chahín & C. Taútiva.
    XIII Latin-iberoamerican Conference in Operations Research (CLAIO), Montevideo, Uruguay, 2006.


Current courses
  • Operations Research (OR343)
Past courses
Courses at other institutions:
  • Optimization
  • Stochastic Processes
  • Computer Networks


LINE: an open-source solver for queueing network models based on ordinary differential equations. Binaries, source and documentation available from the LINE website.

LINE can be integrated with the Palladio Bench suite for the QoS analysis of software applications. LINE is based on the concept of mean-field theory, in which the interactions among a large population of entities are approximated by a single averaged effect.

More details on this tool can be found on the paper:
Assessing SLA compliance from Palladio component models
J. F. Pérez and G. Casale. Proceedings of the 2nd Workshop on Management of resources and services in Cloud and Sky computing (MICAS), 2013.

Q-MAM: A MATLAB toolbox for solving Infinite Queues using Matrix Analytic Methods (Download). This tool requires the SMCSolver tools, which can be found here.

This tool is composed of a set of MATLAB functions (i.e., .m files) to compute the queue length, waiting time and delay distributions of various queueing systems of infinite size. It includes, among others, implementations of the following queueing models, both in discrete and continuous time: PH/PH/1, MAP/MAP/1, MAP/M/c, MAP/D/c, RAP/RAP/1, MMAP[K]/PH[K]/1, MMAP[K]/SM[K]/1, SM[K]/PH[K]/1. State-of-the-art solution techniques are used to solve these models efficiently.

More details on this tool can be found on the paper:
Q-MAM: A Tool for Solving Infinite Queues using Matrix-Analytic Methods,
J.F. Pérez, J. Van Velthoven and B. Van Houdt.

jMarkov and jPhase: object-oriented tools for modeling and solving large-scale Markov Chains and represent Phase-Type distributions. (Download).

This tool facilitates the development of large-scale Markov chains. It is composed of four modules: jMarkov (to build and analyze Markov chains); jQBD (for Quasi-Birth-and-Death processes); jPhase (to represent Phase-Type distributions); and jMDP (for Markovian Decision Processes).

More details on these tools can be found on the papers:
jMarkov: An Object Oriented Framework for Modeling and Analyzing Markov Chains and QBDs,
G. Riaño and J. Góez. Proceedings of the SMCtools’06, October 2006.

jPhase: an object- oriented tool for modeling Phase-Type distributions,
J. F. Pérez and G. Riaño. Proceedings of the SMCtools’06, October 2006.

Editorial Service

  • DCPerf 2014 - The 4th international workshop on Data Center Performance. TPC Member.
  • CLOSER 2014 - The 4th International Conference on Cloud Computing and Services Science. TPC Member.
  • MultiCloud 2014 - Special Session on Multi-Clouds.
  • MAM8 - 8th International Conference on Matrix Analytic Methods. TPC Member.
  • ICPE 2013 - The 4th ACM/SPEC International Conference on Performance Engineering. Registration Chair.
  • CCGrid 2013 - 13th IEEE/ACM International Symposium on Cluster, Cloud and Grid Computing.
  • ICAC 2013 - 10th International Conference on Autonomic Computing
  • QEST 2013 - 10th International Conference on Quantitative Evaluation of SysTems
  • ASMTA 2013 - Twentieth International Conference on Analytical & Stochastic Modelling Techniques & Applications.
  • PDS-DSN 2013 - 43rd Annual IEEE/IFIP International Conference on Dependable Systems and Networks (DSN) - Performance and Dependability Symposium (PDS)
  • DCPerf 2013 - The 3rd international workshop on Data Center Performance
  • ACM Performance Evaluation Review.
  • IEEE/OSA Journal of Optical Communications and Networking.
  • IEEE Communication Letters.
  • The Computer Journal.
  • International Journal of Systems Science.
  • DCPerf 2011 - The first international workshop on Data Center Performance


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