Filled out the maxskew variable which wasn't being set.

Also added a private parameter "info", at the moment it can take the values
none or load, if load is chosen it shows the actual load on each processor.

I want to add more options for printing out the local domain etc on each processor.

Documented the maxskew variable, and how to spot if you are using MPI or not.


git-svn-id: http://svn.cactuscode.org/arrangements/CactusPUGH/PUGH/trunk@355 b61c5cb5-eaca-4651-9a7a-d64986f99364

1 files changed, 62 insertions, 0 deletions

diff --git a/doc/documentation.tex b/doc/documentation.tex
index ac5251f..73982d0 100644
--- a/doc/documentation.tex
+++ b/doc/documentation.tex
@@ -65,6 +65,8 @@ PUGH can be compiled with or without MPI. Compiling without MPI results
 in an executable which can only be used on a single processor, compiling 
 with MPI leads to an executable which can be used with either single or
 multiple processors.
+(Section~\ref{pugh_understanding} describes how you can tell if your
+executable has been compiled with or without MPI).
 
 For configuring with MPI, see the Cactus User's Guide.
 
@@ -177,6 +179,66 @@ pugh::partition_2d_y=''15:15''
 
 
 Note that an empty string for a direction will apply the automatic distribution.
+\section{Understanding PUGH Output}
+
+\label{pugh_understanding}
+
+PUGH reports information about the processor decomposition to standard output 
+at the start of a job. This section described how to interpret that output.
+
+\vskip .3cm
+
+\noindent
+{\bf Single Processor (no MPI)}
+
+\begin{itemize}
+
+\item{\bf Type of evolution}
+
+If an executable has been compiled for only single processor use
+(without MPI), the first thing which PUGH reports is this fact:
+
+{\tt INFO (PUGH): Single processor evolution}
+
+\end{itemize}
+
+
+\vskip .3cm
+
+\noindent
+{\bf Multiple Processor (with MPI)}
+
+
+
+\vskip .3cm
+
+\begin{itemize}
+
+\item{\bf Type of evolution}
+
+If an executable has been compiled using MPI, the first thing which 
+PUGH reports is this fact, together with the number of processors
+being used:
+
+{\tt INFO (PUGH): MPI Evolution on 3 processors}
+
+
+\item{\bf Maximum load skew} 
+
+The maximum load skew describes the variance in the number of gridpoints on
+each processor, and is defined by
+
+$$\mbox{Max Skew} = 100 \;\;\frac{\mbox{Max Points}- \mbox{Min Points}}{\mbox{Average Points}} $$
+
+For most purposes, the maximum skew should ideally be close to zero,
+however if your simulation has a different load at different grid
+points, or if you are running across processors with different
+properties, the optimal skew could be quite different.
+
+By default, PUGH tries to minize the skew in gridpoints, however this may
+be overriden by performing the load balancing manually.
+
+\end{itemize}
 
 \section{Useful Parameters}