DASH, the C++ Template Library for Distributed Data Structures with Support for Hierarchical Locality for HPC and Data-Driven Science
A C++ Template Library for Distributed Data Structures with Support for Hierarchical Locality for HPC and Data-Driven Science.
Exascale systems are scheduled to become available in 2018-2020 and will be characterized by extreme scale and a multilevel hierarchical organization.
Efficient and productive programming of these systems will be a challenge, especially in the context of data-intensive applications. Adopting the promising notion of Partitioned Global Address Space (PGAS) programming the DASH project develops a data-structure oriented C++ template library that provides hierarchical PGAS-like abstractions for important data containers (multidimensional arrays, lists, hash tables, etc.) and allows a developer to control (and explicitly take advantage of) the hierarchical data layout of global data structures.
In contrast to other PGAS approaches such as UPC, DASH does not propose a new language or require compiler support to realize global address space semantics. Instead, operator overloading and other advanced C++ features are used to provide the semantics of data residing in a global and hierarchically partitioned address space based on a runtime system with one-sided messaging primitives provided by MPI or GASNet.
As such, DASH can co-exist with parallel programming models already in widespread use (like MPI) and developers can take advantage of DASH by incrementally replacing existing data structures with the implementation provided by DASH. Efficient I/O directly to and from the hierarchical structures and DASH-optimized algorithms such as map-reduce are also part of the project. Two applications from molecular dynamics and geoscience are driving the project and are adapted to use DASH in the course of the project.
DASH is funded by the German Research Foundation (DFG) under the priority programme "Software for Exascale Computing - SPPEXA" (2013-2018).
See guidelines in CONTRIBUTING.md.
DASH installations are available as Docker containers or build from source using CMake.
For pre-build Docker container images, see the DASH project on Docker Hub.
DASH is built using CMake.
Build scripts are provided for typical DASH configurations and can serve as starting points for custom builds:
Script file name
build.sh| Standard release build
build.dev.sh| Development / debug build
build.mic.sh| Release build for Intel MIC (Xeon Phi)
Optional third-party libraries directly supported by DASH:
DASH is hosted on Github at https://github.com/dash-project/dash and makes use of git submodules to include third-party software (mainly the GoogleTest framework required for building the tests). The build environment will take care of cloning the submodules upon first invocation. However, there might be cases where recursive cloning is required, e.g., if there is no internet access available during the configuration step.
In that case, please use a recursive clone:
(dash/)$ git clone --recursive https://github.com/dash-project/dash.git
To build the DASH project using CMake with default build settings, run:
(dash/)$ cmake --build .
Or, specify a new directory used for the build:
(dash/)$ mkdir build && cd ./build
For a list of available CMake parameters:
(build/)$ cmake .. -L
Parameters can be set using
-Dflags. As an example, these parameters will configure the build process to use icc as C compiler instead of the default compiler:
(build/)$ cmake -DCMAKE_C_COMPILER=icc ..
To configure build parameters using ccmake:
(build/)$ ccmake ..
DASH provides the following variants:
The build process creates the following libraries:
By default, DASH is configured to build all variants of the runtime. You can specify which implementations of DART to build using the cmake option
(build/)$ cmake -DDART_IMPLEMENTATIONS=mpi,shmem ...
Programs using DASH select a runtime implementation by linking against the respective library.
The most reliable method to build DART-MPI with a specific MPI installation is to specify the CMake options
(build/) $ cmake -DMPI_C_COMPILER=/path/to/mpi/bin/mpicc \ -DMPI_CXX_COMPILER=/path/to/mpi/bin/mpiCC \ ...
Source code of usage examples of DASH are located in
dash/examples/. Examples each consist of a single executable and are built by default. Binaries from examples and unit tests are deployed to the build direcory but will not be installed. To disable building of examples, specify the cmake option
(build/)$ cmake -DBUILD_EXAMPLES=OFF ...
To disable building of unit tests, specify the cmake option
(build/)$ cmake -DBUILD_TESTS=OFF ...
The example applications are located in the bin/ folder in the build directory.
The default installation path is
$HOME/optas users on HPC systems typically have install permissions in their home directory only.
To specify a different installation path, use
(build/)$ cmake -DINSTALL_PREFIX=/your/install/path ../
-DINSTALL_PREFIX=can also be given in Step 1.
The installation process copies the 'bin', 'lib', and 'include' directories in the build directory to the specified installation path.
(dash/)$ cmake --build . --target install
Or manually using make:
(build/)$ cmake ../ (build/)$ make (build/)$ make install
DASH provides wrapper scripts that ensure correct include paths as well as linking for all required DASH, DART, and third-party libraries.
The wrappers are named as
dash-c++, depending on the DASH variant activated at build time, e.g., for the MPI variant the wrapper will be called
dash-mpic++(and its aliases
To build a DASH (MPI) application, replace the call to the MPI C++ compiler with a call to
dash-mpicxx(or its alias
$ CXX=dash-mpicxx make
The compiler wrapper currently provides two options: -
--dash:verbosewill cause all invocations of the underlying compiler to be printed to the console. -
--dash:nocppflagsdisables passing DASH-related precompiler flags to the underlying compiler, including flags that control DASH verbosity (if enabled during DASH build) and assertions.
All other parameters will be passed to the underlying compiler, allowing you to control optimization flags and pass precompiler options.
Note that the compiler wrappers also set the language standard to C++11.
With the MPI variant, applications are spawn by MPI:
$ mpirun -mpi
For CUDA and SHMEM, use
$ dartrun-cuda -cuda
$ dartrun-shmem -shmem
Launch the DASH unit test suite using
(dash/shmem/bin/)$ dartrun-shmem dash-test-shmem
(dash/mpi/bin/)$ mpirun dash-test-mpi
For example, you would all unit tests of matrix data structures on 4 units using the MPI runtime with:
(dash/mpi/bin/)$ mpirun -n 4 dash-test-mpi --gtest_filter="MatrixTest*"
or all tests except for the Array test suite:
(dash/mpi/bin/)$ mpirun -n 4 dash-test-mpi --gtest_filter="-ArrayTest*"
LD_PRELOADto run a DASH application built with the DART-MPI backend:
$ LD_PRELOAD=/$IPM_HOME/lib/libipm.so mpirun -n
Available options for IPM are documented in the IPM user guide.
The DASH project homepage: http://www.dash-project.org
The Munich Network Management homepage: http://www.mnm-team.org