X-Git-Url: https://bilbo.iut-bm.univ-fcomte.fr/and/gitweb/loba-papers.git/blobdiff_plain/77dfff6971a1d64b3274379ad340410840d24980..31bff00ae28d5928a2a488e207cac24bcd2a11d7:/supercomp11/supercomp11.tex?ds=sidebyside diff --git a/supercomp11/supercomp11.tex b/supercomp11/supercomp11.tex index b0d23b0..2d6b32f 100644 --- a/supercomp11/supercomp11.tex +++ b/supercomp11/supercomp11.tex @@ -49,7 +49,7 @@ Moreover, asynchronous iterative algorithms in which an asynchronous load balancing algorithm is implemented most of the time can dissociate messages concerning load transfers and message concerning load information. In order to increase the converge of a load balancing algorithm, we propose a simple -heuristic called \emph{virtual load} which allows a node that receives an load +heuristic called \emph{virtual load} which allows a node that receives a load information message to integrate the load that it will receive later in its load (virtually) and consequently sends a (real) part of its load to some of its neighbors. In order to validate our approaches, we have defined a simulator @@ -75,9 +75,11 @@ algorithm which is definitively a reference for many works. In their work, they proved that under classical hypotheses of asynchronous iterative algorithms and a special constraint avoiding \emph{ping-pong} effect, an asynchronous iterative algorithm converge to the uniform load distribution. This work has -been extended by many authors. For example, -DASUD~\cite{cortes+ripoll+cedo+al.2002.asynchronous} propose a version working -with integer load. {\bf Rajouter des choses ici}. +been extended by many authors. For example, Cortés et al., with +DASUD~\cite{cortes+ripoll+cedo+al.2002.asynchronous}, propose a +version working with integer load. This work was later generalized by +the same authors in \cite{cedo+cortes+ripoll+al.2007.convergence}. +{\bf Rajouter des choses ici}. Although the Bertsekas and Tsitsiklis' algorithm describes the condition to ensure the convergence, there is no indication or strategy to really implement @@ -183,12 +185,13 @@ condition or with a weaker condition. \section{Best effort strategy} \label{Best-effort} -We will describe here a new load-balancing strategy that we called -\emph{best effort}. The general idea behind this strategy is, for a -processor, to send some load to the most of its neighbors, doing its +In this section we describe a new load-balancing strategy that we call +\emph{best effort}. The general idea behind this strategy is that each +processor, that detects it has more load than some of its neighbors, +sends some load to the most of its less loaded neighbors, doing its best to reach the equilibrium between those neighbors and himself. -More precisely, when a processors $i$ is in its load-balancing phase, +More precisely, when a processor $i$ is in its load-balancing phase, he proceeds as following. \begin{enumerate} \item First, the neighbors are sorted in non-decreasing order of their @@ -265,6 +268,31 @@ C'est l'algorithme~2 dans~\cite{bahi+giersch+makhoul.2008.scalable}. \section{Virtual load} \label{Virtual load} +In this section, we present the concept of \texttt{virtual load}. In order to +use this concept, load balancing messages must be sent using two different kinds +of messages: load information messages and load balancing messages. More +precisely, a node wanting to send a part of its load to one of its neighbors, +can first send a load information message containing the load it will send and +then it can send the load balancing message containing data to be transfered. +Load information message are really short, consequently they will be received +very quickly. In opposition, load balancing messages are often bigger and thus +require more time to be transfered. + +The concept of \texttt{virtual load} allows a node that received a load +information message to integrate the load that it will receive later in its load +(virtually) and consequently send a (real) part of its load to some of its +neighbors. In fact, a node that receives a load information message knows that +later it will receive the corresponding load balancing message containing the +corresponding data. So if this node detects it is too loaded compared to some +of its neighbors and if it has enough load (real load), then it can send more +load to some of its neighbors without waiting the reception of the load +balancing message. + +Doing this, we can expect a faster convergence since nodes have a faster +information of the load they will receive, so they can take in into account. + +\textbf{Question} Est ce qu'on donne l'algo avec virtual load? + \section{Simulations} \label{Simulations}