Team Sardes

Overall Objectives
Scientific Foundations
Application Domains
New Results
Contracts and Grants with Industry
Other Grants and Activities

Section: New Results

System support

Participants : Renaud Lachaize, Vivien Quéma, Alan Schmitt, Jean-Bernard Stefani, Fabien Gaud, Sylvain Geneves, Willy Malvaud, Alessio Pace, Quentin Sabah, Valerio Schiavoni.

Support for event-based programming in multicore systems

Many high-performance communicating systems are designed using the event-driven paradigm. As multicore platforms are now pervasive, it becomes crucial for such systems to take advantage of the available hardware parallelism. Event-coloring is a promising approach in this regard. First, it allows programmers to simply and progressively inject support for the safe, parallel execution of multiple event handlers through the use of annotations. Second, it relies on a workstealing algorithm to dynamically balance the execution of event handlers on the available cores. We have studied the impact of the workstealing algorithm on the overall system performance. We have showed that the only existing workstealing algorithm designed for event-coloring runtimes is not always efficient: for instance, it causes a 33% performance degradation on a Web server. We have introduced several enhancements to improve the workstealing behavior. An evaluation using both microbenchmarks and real applications, a Web server and the Secure File Server (SFS), shows that our system consistently outperforms a state-of-the-art runtime (Libasync-smp), with or without workstealing. In particular, our new workstealing improves performance by up to +25% compared to Libasync-smp without workstealing and by up to +73% compared to the Libasync-smp workstealing algorithm, in the Web server case. This work is described in the research report [47] .

Gossip-based protocols

Gossip-based information dissemination protocols are considered easy to deploy, scalable and resilient to network dynamics. They are also considered highly ßexible, namely tunable at will to increase their robustness and adapt to churn. So far however, they have mainly been evaluated through simulation, very often assuming ideal settings. In collaboration with Rachid Guerroui's group at EPFL and the INRIA ASAP team, we have developed variants of gossip protocols better suited to real-world settings. We have obtained results in two directions:


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