We are pleased to announce the fifth release (code name +"Lovelace") of the +Einstein Toolkit, an open, community developed software infrastructure for +relativistic astrophysics. This release includes beginning support for OpenCL +(disabled by default). In addition, bug fixes accumulated since the previous +release in October 2011 have been included.
+ +The Einstein Toolkit is a collection of software components and tools for +simulating and analyzing general relativistic astrophysical systems that bui= lds +on numerous software efforts in the numerical relativity community including +CactusEinstein, the Carpet AMR infrastructure and the relativistic +hydrodynamics code GRHydro (an updated and extended version of the public +release of the Whisky code). The Cactus Framework is used as the underlying +computational infrastructure providing large-scale parallelization, general +computational components, and a model for collaborative, portable code +development. The toolkit includes modules to build complete codes for +simulating black hole spacetimes as well as systems governed by relativistic +hydrodynamics.
+ +The Einstein Toolkit uses a distributed software model and its different +modules are developed, distributed, and supported either by the core team of +Einstein Toolkit Maintainers, or by individual groups. Where modules are +provided by external groups, the Einstein Toolkit Maintainers provide quality +control for modules for inclusion in the toolkit and help coordinate support. +The Einstein Toolkit Maintainers currently involve postdocs and faculty from +five different institutions, and host weekly meetings that are open for anyo= ne +to join in.
+ +Guiding principles for the design and implementation of the toolkit inclu= de: +open, community-driven software development; well thought out and stable +interfaces; separation of physics software from computational science +infrastructure; provision of complete working production code; training and +education for a new generation of researchers.
+ +For more information about using or contributing to the Einstein +Toolkit, or to join the Einstein Toolkit Consortium, please visit our +web pages at +<http://einsteintoolkit.org>= ;.
+ +The Einstein Toolkit is primarily supported by NSF +0903973/0903782/0904015 (CIGR), and also by NSF 0701566/0855892 +(XiRel), 0721915 (Alpaca), 0905046/0941653 (PetaCactus), and 0710874 +(LONI Grid).
+ +The Einstein Toolkit contain over 170 regression test cases. +On a large portion of the tested machines, all of these +testsuites pass, +using both MPI and OpenMP parallelisation.
+ +This release of the Einstein Toolkit adds support for GPUs and other +accelerators. This support comprises three levels of abstraction, ranging fr= om +merely building and running both CUDA and OpenCL code, to automated code +generation targetting GPUs instead of CPUs. As with any other programming +paradigm (such as MPI or OpenMP), the performance benefits depend on the +particular algorithms used and optimisations that are applied. In addition, = the +Simulation Factory greatly aids portability to a wide range of computing +systems.
+ +At the lowest level, Cactus now supports compiling, building, and running +with either CUDA or OpenCL. CUDA is supported as new language in addition to= C, +C++, and Fortran; OpenCL is supported as an external library, and builds and +executes compute kernels via run-time calls. Details are described in the +user's guide (for CUDA) and in thorn ExternalLibraries/OpenCL (for OpenCL).<= /p> + +
Many accelerator platforms today separate between host memory and device +memory, and require explicit copy or map operations to transfer data. An +intermediate level of abstraction aids transferring grid variables between h= ost +and device, using schedule declarations to keep track of which data are need= ed +where, and minimising expensive data transfers. For OpenCL, there is a compa= ct +API to build and execute compute kernels at run time. Details are described = in +thorns CactusUtils/Accelerator and CactusUtils/OpenCLRunTime (with example +parameter file).
+ +Finally, the code generation system Kranc has been extended to be able to +produce either C++ or OpenCL code, based on the infrastructure described abo= ve. +This allows writing GPU code in a very high-level manner. However, it needs = to +be stated that the efficiency of the generated code depends on many variable= s, +including e.g. the finite differencing stencil radius and the number of +operations in the generated compute kernels. Non-trivial kernels typically +require system-dependent tuning to execute efficiently, as GPUs and other +accelerators generally show a rather unforgiving performance behaviour. The +thorns McLachlan/ML_WaveToy and McLachlan/ML_WaveToy_CL are examples, genera= ted +from the same Kranc script, showing the generated C++ and OpenCL code.
+ ++
To upgrade from the previous release, use GetComponents with the new +thornlist to check out the new version. GetComponents can also be used to +update an existing checkout, but since some components might have changed +location or have been removed from the toolkit you should try a new checkout +whenever possible instead.
+ +See the Download pag= e on +the Einstein Toolkit website for download instructions.
+ +All repositories participating in this release carry a branch +ET_2012_05 marking this release. These release branches will +be updated if severe errors are found.
+ +This release has been tested on about twenty systems and +architectures, including the following:
+ +The Simulation +Factory contains ready-to-use configuration details for more than +40 additional systems, including most HPC systems +at LONI, +NERSC, +RZG, +and XSEDE (TeraGrid).
+ +The Einstein Toolkit web site contains online documentation for its +components, and pointers for using it to build your own code. There is +also a tutorial that explains how to download, build, and run the code +for a simple binary black hole evolution. We invite you to join our +mailing list +<users(a)einsteintoolkit.org>.
+ +On behalf of the Einstein Toolkit Consortium: the "Lovelace" Release Team=
+ +
+ Eloisa Bentivegna
+ Tanja Bode
+ Peter Diener
+ Roland Haas
+ Ian Hinder
+ Frank Löffler
+ Bruno Mundim
+ Christian D. Ott
+ Erik Schnetter
+
May 28, 2012
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