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author | jthorn <jthorn@f88db872-0e4f-0410-b76b-b9085cfa78c5> | 2003-01-17 12:21:27 +0000 |
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committer | jthorn <jthorn@f88db872-0e4f-0410-b76b-b9085cfa78c5> | 2003-01-17 12:21:27 +0000 |
commit | 3676ea9be7815d1a1b944eb98efa3c9918c6df2e (patch) | |
tree | 76692d54745e5b285e86fe5dd65fa3e7d9f6cd28 | |
parent | 64e9063e97a60d26f672166b61e390e9b8eb3680 (diff) |
document how performance scales with number of processors
git-svn-id: http://svn.einsteintoolkit.org/cactus/EinsteinAnalysis/AHFinderDirect/trunk@923 f88db872-0e4f-0410-b76b-b9085cfa78c5
-rw-r--r-- | doc/documentation.tex | 26 |
1 files changed, 14 insertions, 12 deletions
diff --git a/doc/documentation.tex b/doc/documentation.tex index e03538e..ba0439c 100644 --- a/doc/documentation.tex +++ b/doc/documentation.tex @@ -272,18 +272,20 @@ here's what works and what doesn't: these thorns compiled into your configuration and activated. \item \thorn{AHFinderDirect} works in multi-processor Cactus runs, but at present it's quite inefficient for large numbers of - processors. (It exhibits ``anti-scaling'' with the number - of processors: the run time gets {\em larger\/} as the number - of processors increases.)%%% -\footnote{%%% - The run time on $N$ processors should be roughly - $\alpha + \beta N$ for some (positive!) constants - $\alpha$ and $\beta$. I estimate the value of $N$ - for which the run time is twice the single-processor - value, to be on the order of 10 to 20 for the current - implementation.%%% - }%%% -{} I hope to fix this inefficiency soon. + processors. In fact, it exhibits ``anti-scaling'' with the + number of processors: the run time is {\em larger\/} as the + number of processors increases. I hope to fix this inefficiency + soon, but for now, the run time relative to the single-processor + case is roughly + \begin{flushleft} + \begin{tabular}{cc} + $N$ & $t_N / t_1$ \\ + \hline + 2 & 1.4 \\ + 4 & 2.0 \\ + $N>4$ & $1.55 + 0.12N$ %%%\\ + \end{tabular} + \end{flushleft} \end{itemize} %%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%%% |