A platform description is a human- and machine-readable data sheet describing the main structure and parameters of a computer system's hardware and system software for retargetable toolchains for analysis and optimization.

XPDL is a formal modeling language for describing the structure and properties of computer systems as far as relevant for modeling, analysis and optimization of programs and system configurations for improved performance and energy usage.
XPDL allows to model the structure of clusters, servers with accelerators, embedded computing devices, processors, accelerators and memory units and their interconnects, as well as static principles of their behavior, such as power domains and power state machines. Beyond hardware modeling, platform specifications also include descriptions of installed system software, such as libraries, compilers, runtime systems and operating systems.

XPDL allows for modeling at the meta-level (e.g., new processor types) as well as instantiations at the base level (e.g., concrete server installations).
XPDL uses XML syntax; its hierarchical structure reflects the hierarchy of complex computer systems.
XPDL leverages inheritance and hyperlinks to increase reuse of submodels and to create a world-wide web of platform specifications,

The main purpose of XPDL is to promote retargetability in generic toolchains for performance and energy optimization, as being developed e.g. in the EU FP7 EXCESS project.

• XML syntax
• Hierarchical modeling of both hardware and system software entities
• Models at meta level (type models) and at base level (instances)
• Multiple inheritance
• Hyperlinks for creating a distributed web of platform descriptions
• Formal parameters, constants, constraints
• Predefined model elements for describing processors, cores, memory hierarchy, interconnection networks, devices, GPUs, instruction sets, ... and their hierarchical composition
• Energy modeling: Predefined model elements for describing power domains and power state machines
• Links to microbenchmarks and automatic generation of microbenchmarking driver code for determining unspecified parameter values
• Query API for browsing and querying an aggregated system description at compile time and at runtime.
• Open-source toolchain for model processing, under development

Publications

• Christoph Kessler, Lu Li, Aras Atalar, Alin Dobre:
  XPDL: Extensible Platform Description Language to Support Energy Modeling and Optimization.
  2015 International Workshop on Embedded Multicore Systems (ICPP-EMS'15), in conjunction with ICPP-2015, Beijing, Sep. 1-4, 2015.
  In: Proc. 44th International Conference on Parallel Processing Workshops, pages 51-60, IEEE, 2015. DOI: 10.1109/ICPPW.2015.17.

  • Presentation slides (PDF)
  
  Also presented at SCOPES'16, Germany, May 2016.

• Usman Dastgeer and Christoph Kessler:
  Conditional component composition for GPU-based systems.
  Proc. Seventh Workshop on Programmability Issues for Multi-Core Computers (MULTIPROG-2014) at HiPEAC-2014, Vienna, Austria, Jan. 2014.

• XPDL poster (PDF, A4 version) presented at HiPEAC'16, Prague

XPDL Toolchain Source Code and Documentation

• Current version: XPDL toolchain v0.8
  Access to source-code on request, please contact us by e-mail.

LGPL v3

See the above publications for XPDL example models.

XPDL is a work in progress. Future work includes adding support for modeling more features and properties, supporting model visualization and graphical editing, and conversion tools.

If you would like to contribute, please let us know.

• Lu Li
• Prof. Christoph Kessler

This work was partly funded by the EU FP7 project EXCESS and by SeRC project OpCoReS.