« Sur la santé au travail nous ne renoncerons pas ! »

Le lundi 4 décembre 2017, participant à une « Assemblée nationale pour les CHSCT », 160 militants pour la santé au travail, syndicalistes et professionnels, se retrouvaient pour dire leur colère de la suppression des CHSCT sous couvert d'une fusion des instances représentatives du personnel. Depuis, la loi du 29 mars 2018 (loi de ratification des 6 ordonnances dites « Travail ») a confirmé la mesure parmi d'autres, donnant en outre la possibilité d'accélérer le processus (art. 5) si les mandats actuels n'arrivent à échéance qu'en 2019. Les Comités d'Hygiène, Sécurité, Conditions de travail, n'existeront bientôt plus dans le privé, sauf catégories d'entreprises particulières. Plus vite encore que nous ne l'attendions, leur disparition est aussi à l'ordre du jour dans le secteur public

La « numéritude » volontaire ?

Texte publié dans le dossier "Le travail à l’heure du numérique" du Mensuel du Snesup, 652, février 2017, pages 11-12.Le numérique est un outil qui doit permettre de travailler mieux. Il augmente la productivité, c’est-à-dire qu’il permet de produire plus en moins de temps. Il devrait donc être l’occasion de diminuer le temps de travail, d’accorder plus de temps à des activités choisies, et de partager les richesses ainsi produites. Sinon, à quoi bon 

A New class of algorithms for software pipelining with resource constraints

Projet CHLOEThis report presents a new class of algorithms for loop software pipelining in the presence of resource constraints. This new approach allows to generate optimal code with restect to throughput even for processors with complex resource constraints which make them hard to program even by hand. It consists of two steps : first, we build the reservation table for the body of the software pipelined loop by packing the elementary reservation tables of the different tasks as if the tasks were independent, the length of the global reservation tables then determines the throughput of the loop, second we determine the schedule of each iteration of the loop so that all data dependencies are satisfied and the resource usage conforms with the previously computed reservation table. We show that, in order to reach the optimal throughput (induced by the highest used resource or critical resource), the loop may need to be unrolled. In some important and general cases, we provide theoretical results on the unwinding degree necessary to achieve the optimal throughput. We also show how this class of softaware pipelining algorithms can be used to generate code for the explicitly advanced pipelines found in the Intel i860 processor

Syndicalisme et numérisation, association ou dissociation?

Le syndicalisme, et la FSU en particulier, n'échappe évidemment pas à la numérisation. Or, autant on analyse (un peu) et dénonce la main mise des grands monopoles que sont les "GAFAM" (Google, Apple, Facebook, Amazon, Microsoft), autant l'utilisation de ces outils dans l'activité syndicale n'est pas interrogée. On est au contraire au coeur de multiples injonctions paradoxales

Cyclic Register Pressure and Allocation for Modulo Scheduled Loops

In a previous work, we have introduced the notion of register saturation in directed acyclic graphs (basic blocks) which is the maximal number of registers needed to complete a computation in a multiple issue processor. In this report, we extend our work to the cyclic case¸: given a data dependence graph of a simple loop, the cyclic register saturation is the maximal number of registers needed by any modulo schedule of this DDG. If the register saturation is lower than the number of available registers R, then we can build a software pipelining schedule without including the registers constraints¸: we are sure that any schedule does not need more than R registers, and so no spill code has to be generated. If not, we add some arcs in the DDG such that any modulo schedule would not require more than R registers, while minimizing the critical circuit. Next, we introduce and study the dual notion¸: the cyclic register sufficiency is the minimal number of registers needed by any modulo schedule of the DDG. If this factor is greater than R, spill code cannot be avoided. Finally, we shall show how to construct a cyclic register allocation in the data dependence graph independently from any software pipelined schedule. We insert some anti-depend- ences into the original DDG to express the register reuse relations between statements, such that the number of consumed registers does not exceed R under a fixed execution rate (initiation interval)

SIRA: Schedule Independent Register Allocation for Software Pipelining

International audienceThe register allocation in loops is generally carried out after or during the software pipelining process. This is because doing the register allocation at first step without assuming a schedule lacks the information of interferences between values live ranges. The register allocator introduces extra false dependencies which reduces dramatically the original ILP (Instruction Level Parallelism). In this paper, we give a new formulation to carry out the register allocation before the scheduling process, directly on the data dependence graph by inserting some anti dependencies arcs (reuse edges). This graph extension is first constrained by minimizing the critical cycle and hence minimizing the ILP loss due to the register pressure. The second constraint is to ensure that there is always a cyclic register allocation with the set of available registers, and this for any software pipelining of the new graph. We give the exact formulation of this problem with linear integer programming

La « main invisible » du numérique

Ce texte est un plaidoyer pour que la question du numérique dans la société devienne un débat social, syndical, politique. Ceci nécessite de reconnaître que les enjeux liés au numérique ne sont pas seulement techniques, même s'ils le sont aussi, ce qui demande que chacun.e s'approprie les savoirs scientifiques de base pour être capable de poser des questions légitimes. Sans quoi, le numérique risque de devenir comme la finance : de même que nous parlons de « la main invisible du marché », nous pourrions être soumis à notre insu à cette « main invisible du numérique

Decomposed software pipelining

Projet CHLOEThis report presents a new view on software pipelining in which we consider software pipelining as an instruction level transformation from a vector of one-dimension to a matrix of two-dimensions. Thus, the software pipelining problem can be naturally decomposed into two subproblems, one to determine the row-number of operations in the matrix and another to determine the column-numbers. Using this view-point as a basis, we develop a new loop scheduling approach, called decomposed software pipelining, to exploit instruction-level parallelism for any loop with/without conditional jumps