[Commits] [svn:einsteintoolkit] Paper_EinsteinToolkit_2010/ (Rev. 58)
schnetter at cct.lsu.edu
schnetter at cct.lsu.edu
Sun Apr 17 21:29:23 CDT 2011
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.
Directory Changes:
Directory: /svn:mime-type/
==========================
+ application/octet-stream
File Changes:
Directory: /
============
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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Directory: /local_bibtex/
=========================
File [modified]: references.bib
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===================================================================
--- 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},
}
+
+ at Misc{Cactuscode:BlueGene,
+ note = {Cactus runs on 131,072 cores on Blue Gene/P at ANL},
+ url = {http://cactuscode.org/media/news/BGP-131072/},
+}
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