PhD graduated
Team : ALSOC
Departure date : 12/25/2018

Supervision : Alain GREINER

Co-supervision : WAJSBÜRT Franck

Système de fichiers scalable pour architectures manycores à faible empreinte énergétique

In this thesis we study the problems of implementing a UNIX-like scalable file system on a hardware cache coherent NUMA manycore architecture. To this end, we use the TSAR manycore architecture and ALMOS, a UNIX-like operating system. The TSAR architecture presents, from the operating system point of view, three problems to which we offer a set of solutions. One of these problems is specific to the TSAR architecture while the others are common to existing coherent NUMA manycore.
The first problem concerns the support of a physical memory that is larger than the virtual memory. This is due to the extended physical address space of TSAR, which is 256 times bigger than the virtual address space. To resolve this problem, we modified the structure of the kernel to decompose it into multiple communicating units.
The second problem is the placement strategy to be used on the file system structures. To solve this problem, we implemented a strategy that evenly distributes the data on the different memory banks. The third problem is the synchronization of concurrent accesses to the file system. Our solution to resolve this problem uses multiple mechanisms. In particular, the solution uses an efficient lock-free mechanism that we designed, which synchronizes the accesses between several readers and a single writer.
Experimental results show that: (1) structuring the kernel into multiple units does not deteriorate the performance and may even improve them ; (2) our set of solutions allow us to give performances that scale better than NetBSD ; (3) the placement strategy which distributes evenly the data is the most adapted for manycore architectures.

Defence : 06/28/2016

Jury members :

M. Brice GOGLIN, Inria Bordeaux Sud-Ouest. [Rapporteur]
M. Vivien QUÉMA, Grenoble Laboratoire LIG [Rapporteur]
M. Pierre SENS, Université Pierre & Marie Curie
M. Fabien CLERMIDY, CEA-Leti
M. Alain GREINER, Université Pierre & Marie Curie
M. Franck WAJSBÜRT, Université Pierre & Marie Curie

Departure date : 12/25/2018

2014-2016 Publications