Team VASY

Members
Overall Objectives
Application Domains
Software
New Results
Contracts and Grants with Industry
Other Grants and Activities
Dissemination
Bibliography
Inria / Raweb 2003
Project: VASY

Project : vasy

Section: New Results


Case Studies and Practical Applications

The FAME Cache Coherency Protocol

Participants : Damien Bergamini, Hubert Garavel, Radu Mateescu, Solofo Ramangalahy.

Since October 1998, we have been co-operating with Bull in the framework of the FormalFame contract (see §  7.2) devoted to the use of formal methods for verifying and testing multiprocessor architectures. Our work targets at Fame, the Cc-Numa architecture developed by Bull for its NovaScale series of high-performance servers based on 64 bits Intel Itanium processors. The core of Fame is a complex circuit (named B-sps), which implements the Fame cache coherency protocol and performs routing between processors and input/output nodes. The complexity of this circuit comes both from the internal parallelism inherent to routing and from multiple accesses to shared data, the consistency of which must be preserved.

After studying the B-sps as a whole (1999–2002), FormalFame currently focuses on two complex sub-components of B-sps: the Prr (Pending Request Responses) block and the Ilu (InterLeaving) unit, which are modeled and analyzed in great detail. In 2003, work took place in two directions:

The SCALAGENT Deployment Protocol

Participants : Hubert Garavel, Frédéric Lang, Radu Mateescu, Frédéric Tronel.

In the framework of the Parfums contract (see §  7.3), we studied a deployment protocol designed and implemented by ScalAgent, a startup company originating from the former Sirac team of Inria Rhône-Alpes. Among many potential applications, this protocol can be used to install and configure a set of mobile agents (Java components) on the uninterruptible power supplies manufactured by the Mge-Ups company.

The approach followed for the verification of the deployment protocol consists in generating automatically a formal specification in Lotos for a given configuration of agents to be deployed. The automatic generation is accomplished by a translator that, given as input an Xml file produced by a graphical configuration editor, produces a set of corresponding Lotos processes and an Svl script that drives the verification. The translator takes into account the Java class hierarchy and inheritance relationships to synthesize the dynamic behavior of each agent.

Given the high complexity of the deployment protocol (which features a set of distributed agents, each agent consisting itself of a set of concurrent activities), we chose a compositional verification approach reflecting closely the deployment protocol architecture. Virtually, all tools of Cadp are used during the verification process, including the Bcg_Graph tool (see §  6.1.1) especially developed to generate communication buffers efficiently.

In 2003, we completed the deployment protocol verification, with the following results:

These results led to a publication [25].

The VLTS Benchmark Suite

Participants : Damien Bergamini, Nicolas Descoubes, Hubert Garavel.

In collaboration with the Sen2 team of Cwi (Amsterdam, The Netherlands), we developed and made available to the scientific community the Vlts benchmark suite (see http://www.inrialpes.fr/vasy/cadp/resources/benchmark_bcg.html).

First benchmark base of this kind, Vlts (Very Large Transition Systems) is a collection of forty labeled transition systems of increasing sizes (ranging from 300 states to 34 million states). It provides a scientific criterion for a performance assessment of algorithms and tools operating on large graphs, including graph visualization software, explicit state verification software (model checkers, equivalence checkers, and minimization tools), as well as computer formats for the representation of transition systems. Although very recent, the Vlts benchmark suite has already been used in several scientific publications.

The benchmarks of the Vlts are encoded in the Bcg format and benefit from the specific compression techniques provided by this format. The development of the Vlts benchmark base led us to a finer tuning of the default compression parameters of the Bcg format, resulting in a better compression (approximately 12%). Moreover, we developed additional compression techniques and tools, which decreased the amount of the disk space needed to store the entire Vlts from 800 down to 454 Mbytes.

Other Case Studies

Participants : Damien Bergamini, David Champelovier, Aurore Collomb, Hubert Garavel, Frédéric Lang, Radu Mateescu, Wendelin Serwe, Frédéric Tronel.

In 2003, the Vasy team also worked on the following case studies:

Other teams also used the Cadp toolbox for various case studies. To cite only the work published in 2003, we can mention:

Other research teams took advantage of the software components provided by Cadp (e.g., the Bcg and Open/Cæsar environments) to build their own research software. We can mention the following developments: