Overview
The next two topics will talk about my current research. As of now I am working on the general idea of preparing software for the invasion by heterogeneous cores! My recently concluded internship at IBM Research has been an important reason for my deep involvement in this work as has been the ongoing project at Georgia Tech under my advisor and Prof. Sudhakar Yalamanchili. Towards the end I also describe my Masters thesis at CMU in brief.
Heterogeneous Virtual Machines
A challenge posed by future computer architectures is the efficient exploitation of their many and often, diverse computational cores, with examples ranging from graphics processors, to IBM.s Cell processor, to I/O-centric accelerators sharing chip space with general purpose computational cores like the Cell.s PowerPC cores. This challenge is exacerbated by the diverse facilities for data movement and data sharing across cores resident on such platforms, which range from cache-level methods for data sharing, to non-coherent shared memory with DMA support, to PCI-based connectivity for I/O. The key technical challenge to be addressed by our work is one that deals with the potentially serious mismatch of computational vs. memory or I/O bandwidths present on future platforms. Toward that end, we propose to pursue a course of study that will:
- facilitate the virtualization on such platforms, to exploit the flexibility in what functionality to run where this technology provides and then to use this flexibility both to hide memory bandwidth and I/O latencies and to create the diversity of application behaviors needed to best exploit platform resources;
- create the new system-level technologies needed for virtualizing future heterogeneous many-core machines, including (1) restructuring hypervisor and system functions to create high performance environments for data movement an for accelerator use, (2) scheduling and other resource management support for domains mapped to diverse platform resources, and (3) policy support at hypervisor level to permit efficient resource usage and sharing.
This abstract explains the idea further.
Cellule: Lightweight Virtualization of Accelerators
Initial steps in this research have focused on the efficient use of accelerators, using IBM's Cell BE processor as the key platform addressed by this work. Here, experiences with running the Linux operating system on the Power core of the Cell processor have shown that this core is less efficient than the general purpose cores in hosting a full fledged operating system. In part, this is because the Power core was principally designed to be a `service processor' responsible for coordinating the Cell.s SPEs. The first challenge faced by our research, then, has been to make efficient use of this service processor in order to exploit Cell as a remote accelerator utilized by one or more general purpose machines, with hardware configurations like those in the Roadrunner project. More generally, this research is investigating the opportunities presented by combining the concepts of virtualization and accelerators to simplify the Cell execution model, to enable its effective utilization by the applications running on the general purpose machines.
The first technical outcome of the proposed research is the "Cellule" execution environment (submission). This is a virtualized Cell B.E based system which hosts a small high performance execution environment, called the Special Execution Environment (SEE), on the hypervisor to run SPE applications. To realize this environment, we have ported IBM's research hypervisor (rHype) to work on the Cell board, created wrappers for libSPE, which is the standard interface used by the Cell applications and facilitated the creation of SEE to run the application. The SEE can be compared to a real time OS environment that has exactly the elements necessary for any libSPE based application to run. Initial experimental results have shown that the Cellule environment offers at least as good as or better performance than Linux, which has encouraged our endeavors in this direction.
Area Driven Pervasive Computing Applications
The past few years have witnessed exponential growth in the number of handhelds. Along with the steep rise in the number of handhelds there has also been a tremendous increase in the number of applications and services that have been developed keeping in mind the constraints and flexibilities offered by the mobile devices. A common characteristic that all these applications and services share is that the user has to initiate some action in order to use the results of the application or service. There are hardly any applications that proactively initiate communication with the user. The applications considered in this thesis diverge from these traditional applications and services since the environment is made smart. The idea is to allow the application to specify the areas where it would want to track users and take suitable action in case a user is detected in that area. While much research has focused on developing services architectures for location-aware systems, less attention has been paid to the fundamental and challenging problem of providing capability to an application in defining physical areas where it would want tracking of mobile users, especially in in-building environments. The goal is to be able to determine with high probability when the user is in the area of interest to the application. In this paper we present an infrastructure for area-driven applications enabling them to specify area-based user tracking requirements and achieve the intended purpose. We make use of the existing infrastructure of wireless access points to determine the area where a user is. We also study the improvement that can be brought about in the granularity of an area with the use of history information.
Here is the final presentation.
