When: Thursday, April 03, 10:00 a.m.

Where: 4623 Wean Hall

Milo Martin

SCS Faculty Candidate Talk

Abstract:
Database and web servers are an important part of society's information infrastructure. As the number of clients (e.g., wireless or embedded devices) continues to grow, service providers demand high-performance and cost-effective hardware systems for running server workloads.

Token Coherence is a new hardware technique for increasing the performance of commercial server workloads running on moderate-sized multiprocessors. These shared-memory multiprocessor servers use cache-coherence protocols to provide the abstraction of a unified shared memory. The performance of existing cache-coherence protocols is currently constrained either by requiring global request ordering or by the extra latency added by request indirections.

Token Coherence avoids these performance bottlenecks by decoupling correctness requirements from performance aspects of the system. In this new framework, the correctness substrate uses token counting to explicitly encode read and write permissions, guaranteeing correct shared memory semantics in all cases (without the overhead of indirection or global ordering). A separate performance protocol provides high performance in the common case, relying on a more conservative (less efficient) mechanism only in rare cases. This approach can increase performance, reduce cost, and perhaps reduce protocol design errors. I will also briefly discuss wider applications of this decoupled approach in solving other problems in designing hardware and software systems.

Host: Natassa Ailamaki
For Appointments contact Charlotte Yano (yano@cs.cmu.edu - X8-7656)

Bio: Milo Martin is a PhD candidate and a member of the Wisconsin Multifacet Project (http://www.cs.wisc.edu/multifacet/) at the University of Wisconsin-Madison. Although interested in all aspects of computing systems, his graduate research has focused on hardware techniques to improve multiprocessor cache coherence, memory system performance of commercial workloads, and the use of dynamic feedback to build adaptive and robust systems.

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