DATE: Monday, June 20, 2011 - NOTE SPECIAL DAY
TIME: 11:00 am - 12:00 pm - NOTE SPECIAL TIME
Gates 8102

SPEAKER: Timothy Roscoe (Mothy), ETH Zurich

TITLE: Experience with OS Support for Non-cache-coherent Systems

What should an operating system look like for a multicore computer which is not cache-coherent? It seems increasingly likely that future processor designs will provide only limited "islands" of cache coherence within the machine. This implies OS support for some kind of message passing hardware, either explicit via hardware-supported packets, or implicit via, for example, release-semantics on memory.

We have spent the last 3.5 years building Barrelfish, an open-source research OS targetting scalable, heterogeneous, non-cache-coherent machines. In this talk I will report on our early experiences porting Barrelfish to, and running applications over Barrelfish on, three different experimental non-cache-coherent architectures: the Intel Single-Chip Cloud Computer, the Microsoft Beehive softcore, and traditional 64-bit x86 running under simulation with coherency disabled. I'll talk about the programming and performance challenges in running a single OS across a non-coherent multicore processor, and also speculate on the implications for the design of future hardware support for message-passing.

Timothy Roscoe received a PhD from the Computer Laboratory of the University of Cambridge, where he was a principal designer and builder of the Nemesis operating system, as well as working on the Wanda microkernel and Pandora multimedia system. After three years web-based collaboration systems at a startup company in North Carolina, Mothy joined Sprint's Advanced Technology Lab in Burlingame, California, working on application hosting platforms and networking monitoring. Mothy joined Intel Research at Berkeley in April 2002 as a principal architect of PlanetLab, an open, shared platform for developing and deploying planetary-scale services. In September 2006 he spent four months as a visiting researcher in the Embedded and Real-Time Operating Systems group at National ICT Australia in Sydney, before taking up a Full Professorship at ETH Zurich in January 2007. His current research interests include network architecture and the Barrelfish multicore research operating system.

Visitor Host: Dave Andersen

Visitor Coordinator: Angela Miller

SDI / LCS Seminar Questions?
Karen Lindenfelser, 86716, or visit