X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/mpi-energy2.git/blobdiff_plain/bfe48a883c88e5b63cc724dee3e46d6d18b9a34a..1cea7b40511f60228c23a644b707615cd1559471:/Heter_paper.tex?ds=inline diff --git a/Heter_paper.tex b/Heter_paper.tex index 0203c67..a604b96 100644 --- a/Heter_paper.tex +++ b/Heter_paper.tex @@ -88,9 +88,10 @@ platforms many techniques have been used. Dynamic voltage and frequency scaling consumption. However, lowering the frequency of a CPU might increase the execution time of an application running on that processor. Therefore, the frequency that gives the best trade-off between the energy consumption and the -performance of an application must be selected.\\ -In this paper, a new online frequencies selecting algorithm for heterogeneous -platforms is presented. It selects the frequency which tries to give the best +performance of an application must be selected. + +In this paper, a new online frequency selecting algorithm for heterogeneous +platforms is presented. It selects the frequencies and tries to give the best trade-off between energy saving and performance degradation, for each node computing the message passing iterative application. The algorithm has a small overhead and works without training or profiling. It uses a new energy model for @@ -581,7 +582,7 @@ that node, it is replaced by the nearest available frequency. In Figure~\ref{fig:st_freq}, the nodes are sorted by their computing power in ascending order and the frequencies of the faster nodes are scaled down according to the computed initial frequency scaling factors. The resulting new -frequencies are colored in blue in Figure~\ref{fig:st_freq}. This set of +frequencies are highlighted in Figure~\ref{fig:st_freq}. This set of frequencies can be considered as a higher bound for the search space of the optimal vector of frequencies because selecting frequency scaling factors higher than the higher bound will not improve the performance of the application and it @@ -714,7 +715,7 @@ brute force algorithm. It has a small execution time: for a heterogeneous cluster composed of four different types of nodes having the characteristics presented in Table~\ref{table:platform}, it takes on average \np[ms]{0.04} for 4 nodes and \np[ms]{0.15} on average for 144 nodes to compute the best scaling -factors vector. The algorithm complexity is $O(F\cdot (N \cdot4) )$, where $F$ +factors vector. The algorithm complexity is $O(F\cdot N)$, where $F$ is the number of iterations and $N$ is the number of computing nodes. The algorithm needs from 12 to 20 iterations to select the best vector of frequency scaling factors that gives the results of the next sections. @@ -748,22 +749,22 @@ nodes were connected via an Ethernet network with 1 Gbit/s bandwidth. \caption{Heterogeneous nodes characteristics} % title of Table \centering - \begin{tabular}{|*{7}{l|}} + \begin{tabular}{|*{7}{r|}} \hline Node &Simulated & Max & Min & Diff. & Dynamic & Static \\ type &GFLOPS & Freq. & Freq. & Freq. & power & power \\ & & GHz & GHz &GHz & & \\ \hline - 1 &40 & 2.5 & 1.2 & 0.1 & 20~W &4~W \\ + 1 &40 & 2.50 & 1.20 & 0.100 & \np[W]{20} &\np[W]{4} \\ \hline - 2 &50 & 2.66 & 1.6 & 0.133 & 25~W &5~W \\ + 2 &50 & 2.66 & 1.60 & 0.133 & \np[W]{25} &\np[W]{5} \\ \hline - 3 &60 & 2.9 & 1.2 & 0.1 & 30~W &6~W \\ + 3 &60 & 2.90 & 1.20 & 0.100 & \np[W]{30} &\np[W]{6} \\ \hline - 4 &70 & 3.4 & 1.6 & 0.133 & 35~W &7~W \\ + 4 &70 & 3.40 & 1.60 & 0.133 & \np[W]{35} &\np[W]{7} \\ \hline \end{tabular}