Mathieu Jan

The characteristics and performance of groups of jobs in grids

Even though with few exceptions, grid workloads are dominated by single-node jobs, not all of these jobs are necessarily independent or unrelated. For instance, sets of jobs may be grouped because they are submitted by users in batches, e.g., to perform parameter sweeps. However, there is no reported data to confirm the presence and structure of these groupings, despite the large potential impact of such information. To address this lack of information, in this work we present a first investigation into the characteristics of groups of jobs present in grid workloads. First, we define three types of job groupings: batch, continued, and bursty submissions. Then, we analyze the characteristics of these groupings for three long-term traces from currently deployed grid environments. Notably, our results show that the various groupings are responsible for up to 96% of the total CPU time consumption. Finally, we present insights into the performance of real grids in dealing with grouped jobs.

Performance evaluation of JXTA communication layers

The arrival of the P2P model has opened many new avenues for research within the field of distributed computing. This is mainly due to important practical features (such as support for volatility, high scalability). Several generic P2P libraries have been proposed for building higher-level services. In order to judge the appropriateness of using a generic P2P library for a given application type, an experimental performance evaluation of the provided functionalities is unavoidable. Very few analyses of this kind have been reported, as most evaluations are limited to complexity analyses and to simulations. Such experimental analyses are important, especially when using P2P software in a grid computing context, where applications may have precise efficiency requirements. In this paper, we focus on JXTA, which provides generic building blocks and protocols intended to serve as a basis for specialized P2P services and applications. We perform a performance evaluation of the three communication layers (endpoint, pipe and socket) over a fast Ethernet local-area network, for recent versions of the J2SE and C bindings of JXTA. We provide a detailed analysis explaining the behavior of these three layers and we give hints showing how to efficiently use them.

A practical example of convergence of P2P and grid computing: An evaluation of JXTA’s communication performance on grid networking infrastructures

As the size of todays grid computing platforms increases, the need for self-organization and dynamic reconfiguration becomes more and more important. In this context, the convergence of grid computing and peer-to-peer (P2P) computing seems natural. However, grid infrastructures are generally available as a hierarchical federation of SAN-based clusters interconnected by high-bandwidth WANs. In contrast, P2P systems usually run on the Internet, on top of random, generally flat network topologies. This difference may lead to the legitimate question of how adequate are the P2P communication mechanisms on hierarchical grid infrastructures. Answering this question is important, since it is essential to efficiently exploit the particular features of grid networking topologies in order to meet the constraints of scientific applications. This paper evaluates the communication performance of the JXTA P2P platform over high-performance SANs and WANs, for both J2SE and C bindings. We discuss these results, then we propose and evaluate several techniques able to improve the JXTAs performance on such grid networking infrastructures.