User: eschnett Date: 2011/04/17 09:29 PM
Added: /figures/ carpet-interpolation.pdf, carpet-timestepping.pdf
Modified: / ET.tex /local_bibtex/ references.bib
Log: Update Carpet and Simulation Factory sections.
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File [modified]: ET.tex Delta lines: +57 -16 =================================================================== --- ET.tex 2011-04-12 18:15:09 UTC (rev 57) +++ ET.tex 2011-04-18 02:29:22 UTC (rev 58) @@ -391,13 +391,14 @@ The Einstein Toolkit offers two drivers, \emph{PUGH} and \emph{Carpet}. PUGH provides domains consisting of a uniform grid with Cartesian topology, and is highly scalable (up to more than -130,000 cores on a Blue -Gene/P \todo{cite}). Carpet \cite{Schnetter:2003rb, Schnetter:2006pg, +130,000 cores on a Blue Gene/P \cite{Cactuscode:BlueGene}.) +Carpet \cite{Schnetter:2003rb, Schnetter:2006pg, CarpetCode:web} provides multi-block methods and adaptive mesh refinement (AMR@). Multi-block methods cover the domain with a set of (possibly distorted) blocks that exchange boundary information e.g.\ via interpolation or penalty methods.\footnote{Although multi-block - methods are supported by Carpet, the Einstein Toolkit does not yet + methods are supported by Carpet, the Einstein Toolkit itself + does not yet contain any multi-block coordinate systems.} The AMR capabilities employ the standard Berger-Oliger algorithm \cite{Berger84} with subcycling in time. @@ -425,9 +426,24 @@ interpolation operations are implemented efficiently in Carpet, and are applied automatically as specified in the execution schedule, i.e.\ without requiring function calls in user code. +Figure \ref{fig:carpet-details} describes some details of the +Berger-Oliger time stepping algorithm.
-\todo{ES: Add figure from Carpet paper explaining subcycling in time.} -\todo{ES: Add figure showing a grid structure} +\begin{figure} + \centering + \includegraphics[width=0.45\textwidth]{figures/carpet-timestepping} + \hfill + \includegraphics[width=0.45\textwidth]{figures/carpet-interpolation} + \caption{Berger-Oliger time stepping details, showing a coarse and a + fine grid; time moves upwards. \textbf{Left:} Time stepping + algorithm. First the coarse takes a large time step, then the + refined grid takes two smaller steps. Then, the fine grid solution + is injected into the coarse grid where the grids overlap. + \textbf{Right:} Fine grid boundary conditions. The boundary points + of the refined grids are filled via interpolation. This may + require interpolation in space and in time.} + \label{fig:carpet-details} +\end{figure}
Carpet is the main driver used today for Cactus-based astrophysical simulations. Carpet offers hybrid MPI/OpenMP parallelisation and is @@ -476,10 +492,31 @@ The Simulation Factory supports and simplifies three kinds of operations: \begin{description} -\item[Remote Access] \todo{ES} -\item[Configuring and Building] \todo{ES} -\item[Submitting and Managing Simulations] \todo{ES} +\item[Remote Access] The actual access commands and authentication + methods differ between systems, as do the user names that a person + has on different systems. In addition, some systems are not directly + accessible, but one has to log in to a particular ``trampoline'' + server first. The Simulation Factory hides this complexity. +\item[Configuring and Building] Building Cactus requires certain + software on the system, such as compilers, libraries, or build + tools. Many systems offer different version of these, which may also + be installed in non-default locations. Finding a working combination + of these that results in efficient code is very tedious and requires + low-level system experience. The Simulation Factory provides a + \emph{machine database} that enables users to store and exchange + this information. In many cases, this allows people to begin to use + a new machine in a very short time and with just a few, simple + commands. +\item[Submitting and Managing Simulations] Many simulations run for + days or weeks, requiring frequent checkpointing and job + re-submission because of short queue run time limits. Simple user + errors in these menial tasks can potentially destroy weeks of + information. The Simulation Factory offers safe commands that + encapsulate best practices that prevent many common errors and leave + a log trail. \end{description} +The above features make running simulations on supercomputers much +safer and simpler.
\subsection{Kranc\pages{1 Ian}} \label{sec:kranc} @@ -779,9 +816,9 @@ method to achieve rapid solutions.
\begin{figure} - \label{fig:TP_BHNS_coordinates} \centering\includegraphics[width=0.5\textwidth]{TwoPunctures_grid_BHNS}\ \caption{Example of a TwoPunctures coordinate system for BH-NS binary initial data} + \label{fig:TP_BHNS_coordinates} \end{figure}
\subsubsection{Lorene-based binary data} @@ -814,10 +851,10 @@ at every point.
\begin{figure} - \label{fig:Lorene_coordinates} \centering\includegraphics[width=0.5\textwidth]{Lorene_Grid}\ \caption{Example of a Lorene multi-domain coordinate system for binary initial data. The outermost, compactified domain extending to spatial infinity is not shown.} + \label{fig:Lorene_coordinates} \end{figure}
\codename{Meudon_Bin_BH} can read in binary black hole @@ -836,7 +873,7 @@
\subsubsection{TOVSolver}
-\subsection{Equation of States}\pages{1 Christian} +\subsection{Equations of States}\pages{1 Christian}
\subsection{Spacetime Curvature and Hydrodynamics Evolution} \todo{Christian in charge} @@ -1535,12 +1572,16 @@ \begin{center} \includegraphics{faces} \end{center} - \caption{Recursive transformation of a point $x$ in quadrant 3 to a the - physical point $x''$ for which there is actual data stored. In this - example two reflection symmetries along the horizontal and vertical axis - are present, notice how the vector components are transformed in + \caption{Iterative transformation of a point $x$ in quadrant 3 to the + corresponding + point $x''$ for which there is actual data stored. In this + example, two reflection symmetries along the horizontal and vertical axis + are present. notice how the vector components change in transformations $A$ and $B$. Image courtesy of Erik Schnetter\todo{RH: - Erik, are you ok with this paper re-using your image from SymBase?}} + Erik, are you ok with this paper re-using your image from + SymBase?}\todo{ES: Yes, I think using figures from the Cactus + users' guide is fine. However, this particular image is not from + me.}} \label{fig:faces} \end{figure} Thorn \codename{Boundary} provides basic boundary conditions. A boundary
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File [modified]: references.bib Delta lines: +5 -0 =================================================================== --- local_bibtex/references.bib 2011-04-12 18:15:09 UTC (rev 57) +++ local_bibtex/references.bib 2011-04-18 02:29:22 UTC (rev 58) @@ -29345,3 +29345,8 @@ publisher = {Springer-Verlag}, address = {Berlin, Heidelberg}, } + +@Misc{Cactuscode:BlueGene, + note = {Cactus runs on 131,072 cores on Blue Gene/P at ANL}, + url = {http://cactuscode.org/media/news/BGP-131072/%7D, +}