# HG changeset patch # User Ashwin Vishnu <avmo@kth.se> # Date 1543604537 -3600 # Fri Nov 30 20:02:17 2018 +0100 # Node ID 9bebe5b1e3d786a3ff98cad849c9016c63137450 # Parent a3bcea4ef8576d63dacd00a2aaf4333e4fd090d3 FluidSim: comparison with sequential walltimes diff --git a/fluidsim/fluidsim_paper.tex b/fluidsim/fluidsim_paper.tex --- a/fluidsim/fluidsim_paper.tex +++ b/fluidsim/fluidsim_paper.tex @@ -687,10 +687,12 @@ \subsubsection*{Scalability} Scalability can be quantified by speedup $S$ which is a measure of the time taken -to complete $N$ iterations for different number of processes, $n_p$. We shall -refrain from comparing sequential runs in this context, since the operators used -for the sequential mode differ from the parallel mode, especially the FFT -class. Speedup is formally defined here as: +to complete $N$ iterations for different number of processes, $n_p$. +%We shall +%refrain from comparing sequential runs in this context, since the operators used +%for the sequential mode differ from the parallel mode, especially the FFT +%class. +Speedup is formally defined here as: \begin{equation} S_\alpha(n_p) = \frac @@ -743,6 +745,30 @@ \fluidpack{fft}, namely \codeinline{fft2d.mpi\_with\_fftw1d} and \codeinline{fft2d.mpi\_with\_fftwmpi2d}. +Although the FFT classes are different for sequential and parallel +runs, for the sake of comparison, we have tabulated the actual +walltime elapsed in Table~\ref{table:seqpar}. Clearly due to the differences +in the implementations, for \codeinline{fftw1d}-based classes it takes a +performance hit with parallelization, while for classes based on +\codeinline{fftw2d} the performance improves. + +\begin{table} +\centering +\begin{tabular}{lrlr} +\hline + FFT class & Time ($n_p=1$) & FFT class & Time ($n_p=2$) \\ +\hline + \codeinline{fft2d.with\_fftw1d} & 6.63 & + \codeinline{fft2d.mpi\_with\_fftw1d} & 7.63 \\ + \codeinline{fft2d.with\_fftw2d} & 5.59 & + \codeinline{fft2d.mpi\_with\_fftwmpi2d} & 3.91 \\ +\hline +\end{tabular} +\caption{Elapsed times (in seconds) for twenty time steps of 1024 x 1024 case +with the 2D Navier-Stokes 2D (\codeinline{fluidsim.solvers.ns2d}) solver.} +\label{table:seqpar} +\end{table} + \begin{figure}[htp] \centering \includegraphics[width=\linewidth]{tmp/fig_bench_strong2d}