PhD graduated
Team : REGAL
Departure date : 08/31/2016

Supervision : Pierre SENS

Co-supervision : SOPENA Julien

A kernel cooperative cache for virtualized environments

With the advent of cloud architectures, virtualization has become a key mechanism for ensuring isolation and flexibility. However, a drawback of using virtual machines (VMs) is the fragmentation of physical resources. As operating systems leverage free memory for I/O caching, memory fragmentation is particularly problematic for I/O-intensive applications, which suffer a significant performance drop. In this context, providing the ability to dynamically adjust the resources allocated among the VMs is a primary concern.
To address this issue, this thesis proposes a distributed cache mechanism called Puma. Puma pools together the free memory left unused by VMs: it enables a VM to entrust clean page-cache pages to other VMs. Puma extends the Linux kernel page cache, and thus remains transparent, to both applications and the rest of the operating system. Puma adjusts itself dynamically to the caching activity of a VM, which Puma evaluates by means of metrics derived from existing Linux kernel memory management mechanisms. Our experiments show that Puma significantly improves the performance of I/O-intensive applications and that it adapts well to dynamically changing conditions.

Defence : 02/04/2016

Jury members :

Mme Christine Morin, Directrice de recherche, INRIA [Rapporteur]
M. Vivien Quéma, Professeur, Grenoble INP [Rapporteur]
M. Édouard Bugnion, Professeur, École polytechnique fédérale de Lausanne
M. Gilles Muller, Directeur de recherche, INRIA
M. Étienne Rivière, Maître assistant, Université de Neuchâtel
M. Sébastien Monnet, Maître de conférences (HDR), Université Pierre et Marie Curie
M. Pierre Sens, Professeur, Université Pierre et Marie Curie
M. Julien Sopena, Maître de conférences, Université Pierre et Marie Curie

Departure date : 08/31/2016

2012-2016 Publications