X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/hpcc2014.git/blobdiff_plain/ee24b6afced350626b57accf9d10690bf9667aca..757a3d8174e2736033052c4acc64de277cd66e11:/hpcc.tex?ds=sidebyside diff --git a/hpcc.tex b/hpcc.tex index c48f1f6..da2ec91 100644 --- a/hpcc.tex +++ b/hpcc.tex @@ -1,4 +1,3 @@ - \documentclass[conference]{IEEEtran} \usepackage[T1]{fontenc} @@ -493,7 +492,7 @@ simulates the case of distant clusters linked with long distance network as in g Both codes were simulated on a two clusters based network with 50 hosts each, totaling 100 hosts. Various combinations of the above -factors have provided the results shown in Table~\ref{tab.cluster.2x50}. The problem size of the 3D Poisson problem ranges from $N_x = N_y = N_z = \text{62}$ to 150 elements (that is from +factors have provided the results shown in Table~\ref{tab.cluster.2x50}. The problem size of the 3D Poisson problem ranges from $N=N_x = N_y = N_z = \text{62}$ to 150 elements (that is from $\text{62}^\text{3} = \text{\np{238328}}$ to $\text{150}^\text{3} = \text{\np{3375000}}$ entries). With the asynchronous multisplitting algorithm the simulated execution time is in average 2.5 times faster than with the synchronous GMRES one. %\AG{Expliquer comment lire les tableaux.} @@ -523,7 +522,7 @@ $\text{62}^\text{3} = \text{\np{238328}}$ to $\text{150}^\text{3} = power (GFlops) & 1 & 1 & 1 & 1.5 & 1.5 \\ \hline - size $(n^3)$ + size $(N)$ & 62 & 62 & 62 & 100 & 100 \\ \hline Precision @@ -548,7 +547,7 @@ $\text{62}^\text{3} = \text{\np{238328}}$ to $\text{150}^\text{3} = Power (GFlops) & 1.5 & 1.5 & 1.5 & 1.5 & 1.5 \\ % & 1 & 1.5 \\ \hline - size $(n^3)$ + size $(N)$ & 110 & 120 & 130 & 140 & 150 \\ % & 171 & 171 \\ \hline Precision @@ -647,11 +646,11 @@ Note that the program was run with the following parameters: \begin{itemize} \item Description of the cluster architecture matching the format ; -\item Maximum number of iterations; -\item Precisions on the residual error; +\item Maximum numbers of outer and inner iterations; +\item Outer and inner precisions on the residual error; \item Matrix size $N_x$, $N_y$ and $N_z$; -\item Matrix diagonal value: $6$ (See Equation~(\ref{eq:03})); -\item Matrix off-diagonal value: $-1$; +\item Matrix diagonal value: $6$ (see Equation~(\ref{eq:03})); +\item Matrix off-diagonal values: $-1$; \item Communication mode: asynchronous. \end{itemize} @@ -664,12 +663,12 @@ asynchronous multisplitting compared to GMRES with two distant clusters. With these settings, Table~\ref{tab.cluster.2x50} shows that after setting the bandwidth of the inter cluster network to \np[Mbit/s]{5} and a latency in order of one hundredth of millisecond and a processor power of one GFlops, an efficiency of about \np[\%]{40} is -obtained in asynchronous mode for a matrix size of 62 elements. It is noticed that the result remains +obtained in asynchronous mode for a matrix size of $62^3$ elements. It is noticed that the result remains stable even we vary the residual error precision from \np{E-5} to \np{E-9}. By -increasing the matrix size up to 100 elements, it was necessary to increase the +increasing the matrix size up to $100^3$ elements, it was necessary to increase the CPU power of \np[\%]{50} to \np[GFlops]{1.5} to get the algorithm convergence and the same order of asynchronous mode efficiency. Maintaining such processor power but increasing network throughput inter cluster up to \np[Mbit/s]{50}, the result of efficiency with a relative gain of 2.5 is obtained with -high external precision of \np{E-11} for a matrix size from 110 to 150 side +high external precision of \np{E-11} for a matrix size from $110^3$ to $150^3$ side elements. %For the 3 clusters architecture including a total of 100 hosts, @@ -704,7 +703,7 @@ reach the following two objectives: \item To test the combination of the cluster and network specifications permitting to execute an asynchronous algorithm faster than a synchronous one. \end{enumerate} -Our results have shown that with two distant clusters, the asynchronous multisplitting is faster to \np[\%]{40} compared to the synchronous GMRES method +Our results have shown that with two distant clusters, the asynchronous multisplitting method is faster to \np[\%]{40} compared to the synchronous GMRES method which is not negligible for solving complex practical problems with more and more increasing size. @@ -715,7 +714,7 @@ tool to run efficiently an iterative parallel algorithm in asynchronous mode in a grid architecture. In future works, we plan to extend our experimentations to larger scale platforms by increasing the number of computing cores and the number of clusters. -We will also have to increase the size of the input problem which will require the use of a more powerful simulation platform. At last, we expect to compare our simulation results to real execution results on real architectures in order to experimentally validate our study. +We will also have to increase the size of the input problem which will require the use of a more powerful simulation platform. At last, we expect to compare our simulation results to real execution results on real architectures in order to experimentally validate our study. Finally, we also plan to study other problems with the multisplitting method and other asynchronous iterative methods. \section*{Acknowledgment}