Logiciel propriétaire | EPFL Graph Search

Un logiciel propriétaire, logiciel non libre ou parfois logiciel privatif voire logiciel privateur, est un logiciel qui ne permet pas légalement ou techniquement, ou par quelque autre moyen que ce soit, d'exercer simultanément les quatre libertés logicielles que sont l'exécution du logiciel pour tout type d'utilisation, l'étude de son code source (et donc l'accès à ce code source), la distribution de copies, ainsi que la modification du code source. Les limitations légales, permises par le droit d'auteur, qui s'appliquent aux logiciels, sont choisies par les ayants droit et sont souvent encadrées par un contrat de licence utilisateur final (CLUF), nommé alors licence propriétaire. Elles ont souvent, mais pas toujours, pour objectif de permettre le contrôle de la diffusion du logiciel afin de permettre la vente de licences de logiciels. Un logiciel étant un objet purement numérique, sa copie est souvent aussi simple que la copie de tout autre fichier informatique. Les diffuseurs de lo

Advancing the State of Network Switch ASIC Offloading in the Linux Kernel

Andy Roulin

Modern data-center network operating systems rely on proprietary user-space daemons wrapping SDKs from switch vendors. Linux-based variants of these operating systems have benefited from increasing and simplified dataplane offloading support in recent years: kernel resources such as routes and next hops are offloaded to hardware and the kernel can, e.g., learn new MAC entries seen from the hardware forwarding plane. However, the Linux kernel in these operating systems has to be extended and customized as it still lacks constructs (constructs exposed to user-space or in-kernel constructs) needed for complete control plane processing and dataplane offloading. Managing limited hardware resources and keeping the kernel and hardware forwarding planes equivalent are two examples of challenges where the lack of appropriate constructs forces switch operating systems to use user-space solutions coupled with proprietary SDKs and custom kernel modifications. Filling the gaps, i.e., designing and adding the missing constructs, would enable faster control plane processing (less user-kernel context switches) and faster dataplane configura- tion. It would also encourage in-tree kernel drivers from hardware vendors instead of the current closed-source user-space SDKs which would also improve performance while estab- lishing Linux as the standardized API for network switches. This thesis explores the different designs, performance challenges and trade-offs of completing the in-kernel switching API, starting from switch port configuration, faster control path packet processing and ending with in-kernel ASIC resource management. As most hardware vendors are not yet ready to open their drivers in the kernel, workarounds to still provide support for vendors’ SDKs through the same in-kernel API are presented as well. A user-space switch port driver for Mellanox switches was ported to kernel space in order to accelerate control plane processing and bootstrap the in-kernel switch port configuration design. A prefetching scheme which hides PCI latency was designed to manage limited and shared ASIC resources with synchronous feedback to user-space daemons in case of exhausted resources.

2018

Type-based event dissemination

Sébastien Bähni

With the explosion of broadband Internet connections in the late 80s, new types of applications, called distributed applications, came to light. These applications typically seek to provide a user with remote services that appear to that user as if they were local. For instance, when a user browses the Internet, web pages are downloaded from different servers and are displayed on the screen of the client's computer as if they were directly available on the computer itself. Typically one distinguishes two kinds of actors in such applications: clients, searching for information, and servers, providing the information. Furthermore, there are generally two models of interaction according to which these actors exchange information. In the first model, the client requests specific information and waits until the server replies to it. In the second model, the client registers its interests in some information with a set of servers and is notified when new information is available. Both models have their advantages and disadvantages but the second has obvious asynchrony benefits in a large-scale system in which it is very difficult to know the time taken to answer a request. The second model is usually encapsulated within the celebrated publish/subscribe abstraction. According to this abstraction, clients are either subscribers which express interest in specific information, or publishers which create and send pieces of information usually transmitted in the form of events (e.g., as HTML pages or plain data). The subscriber does not need to know a publisher or to be on-line with it to receive its published events. These properties are sometimes refer to as space and time decoupling respectively. Newsgroups are the most well known example of publish/subscribe system. While indeed appealing, the publish/subscribe abstraction is not easy to implement effectively. There are at least two challenging issues: (1) the representation of the events and (2) their dissemination on a large-scale or in a mobile environment. Events are usually transferred as XML messages or byte arrays. The system must therefore transform events into pieces of software implemented in its underlying language (e.g., Java, C#) before handling them. In addition, the reliable dissemination on a large-scale or in a mobile environment is not trivial, especially as in practice it is necessary to minimize the number of duplicates and parasite events (i.e., events of no interest) to save bandwidth and processing power. We focus in this thesis on devising and implementing algorithms which address the above two issues in publish/subscribe systems implemented in object-oriented languages (e.g., Java, C#) and such that the events that are transferred between the different actors correspond to serialized objects. These systems are also called type-based publish/subscribe systems. We first present techniques to detect events of interest and throw away parasite events. We show that these techniques are of major use for reliably disseminating events either on a large-scale or in a mobile environment without flooding the network. Finally, we illustrate type interoperable rules that let instances of two different types, but still representing the same entity, to be used indistinguishably. Together with the algorithms, we exhibit implementation prototypes and performance measures conducted over them.

EPFL2006

The cost of omnidirectionality: extracting and labelling the echoes

Julien Olivier Thierry Rüegg

This report explains all theoretical and practical aspects of a 2D room re- construction algorithm based on euclidean geometry. Detailed theoretical explanations about the procedure are given in the first part. In the second part, a precise description of the implementational choices, issues, strengths and weaknesses is given in order for the user to run the software correctly and be able to modify and improve it with more simplicity.

2017