Scientific Applications: ChaNGa - Computational Cosmology and N-Body Codes

ChaNGa (Charm N-body GrAvity)

Cosmological simulation framework "ChaNGa" (originally "N-Chilada") is a collaborative project with Prof. Thomas Quinn (University of Washington: N-Body Shop) supported by the NSF.

ChaNGa (CHArm++ N-body GrAvity solver) was built as a Charm++ application that employs a tree algorithm to represent the simulation space. This tree is constructed globally over all particles in the simulation and segmented into elements named TreePieces. The various TreePieces are distributed by the Charm++ runtime system to the available processors for parallel computation of the gravitational forces. Each TreePiece is implemented in ChaNGa as a chare and can migrate between processors (e.g. during load balancing) as the simulation evolves. Because various TreePieces may reside on the same processor, ChaNGa employs a software caching mechanism that accelerates repeated accesses to the same remote particle data. Each processor contains a cache, implemented as a Charm++ group, to store remotely fetched TreePieces. Another important feature in ChaNGa is the use of a multi-step integration scheme, which on the smallest (most frequent) timestep updates only those particles with the highest speeds.

MAJOR GOALS: The main goal of this work is to produce the most scalable code available for Cosmological simulations; to achieve that, load balancing is a fundamental capability, both at singlestepping and at multistepping. Also, achieving good sequential performance is important.

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Historically, this project was called N-Chilada, a framework for enabling N-Body based parallel simulations, and especially those in Cosmology and Astronomy. N-Chilada was a collaborative project with Prof. Thomas Quinn (University of Washington) and Prof. Marianne Winslett (University of Illinois). This research page has been archived and can be found here.
People
Papers/Talks
14-30
2014
[Paper]
Adaptive Techniques for Clustered N-Body Cosmological Simulations [arXiv 2014]
14-18
2014
[Paper]
TRAM: Optimizing Fine-grained Communication with Topological Routing and Aggregation of Messages [ICPP 2014]
13-41
2013
[Paper]
Parallel Science and Engineering Applications: The Charm++ Approach: Chapter 6: N-body Simulations with ChaNGa [Book 2013]
13-16
2013
[Paper]
Parallel Science and Engineering Applications: The Charm++ Approach [Book 2013]
10-16
2010
[Paper]
Scaling Hierarchical N-Body Simulations on GPU Clusters [SC 2010]
08-03
2008
[Paper]
Massively Parallel Cosmological Simulations with ChaNGa [IPDPS 2008]
07-09
2007
[Paper]
Toward Petascale Comological Simulations with ChaNGa [PPL Technical Report 2007]
06-21
2006
[Poster]
Cosmological Simulations on Supercomputers [SC 2006]
06-09
2006
[MS Thesis]
Performance Evaluation of Tree Structures and Tree Traversals for Parallel N-Body Cosmological Simulations [Thesis 2006]
06-01
2006
[Paper]
Scalable Cosmological Simulations on Parallel Machines [VECPAR 2006]
04-19
2004
[Poster]
Salsa: a Parallel, Interactive, Particle-Based Analysis Tool [SC 2004]
| Thomas Quinn | Laxmikant Kale | Filippo Gioachin | Orion Lawlor | Graeme Lufkin | Gregory Stinson