Henry M. Levy Chairman and Wissner-Slivka Chair Department of Computer Science and Engineering University of Washington

Henry M. Levy holds the Wissner-Slivka Chair in Computer Science and Engineering at the University of Washington. Hank's research projects focus on operating systems, distributed and parallel computing, the world-wide web, and computer architecture.

• Vanish: Self-Deleting Data: Our latest work is a system called Vanish that ensures privacy for digital data stored in the cloud. Vanish provides timeouts for digital data stored on Web services, so that all copies of data (even offline copies) simultaneously self-destruct (become unreadable) at a specified future time. We have released our vanish prototype. (See articles in the New York Times and The Economist.)

• Security/Spyware: We have been interested in both characterizing and preventing Spyware threats. SpyProxy uses pre-execution of Web content to detect spyware threats on the fly (see article in InfoWorld). We produced the first quantitative studies of spyware (PDF), and then crawled the Web to study the density of malicious executables and Web pages in different Web categories, e.g., games, celebrity sites, news sites, etc. [PDF] (see article in Science Daily). As well, we designed a new Web browser architecture, called Tahoma, that protects users from malicious Internet content and provides guarantees to Web services. We've also looked at general requirements for browser architectures (see HOTNETS paper).

• Personal Data Sharing and Organization: We are working on ways to facilitate protected, fine-grained sharing of heterogeneous collections of personal data objects, both peer-to-peer (in a system called HomeViews) and using personal data objects that are stored behind protected Web services (in Menagerie).

• Measurement of Internet Behavior and Content Delivery Mechanisms : We have conducted several significant studies of the Internet and the Web, e.g., evaluating peer-to-peer file sharing systems (such as Kazaa and Gnutella), studying sharing of web documents and the potential of cooperative proxy caching, evaluating streaming media protocols, etc.

• Reliable Operating Systems: We built OS infrastructure (called "Nooks") to improve the reliability of commodity operating systems. Nooks allows both the OS and applications to tolerate failures in device drivers -- the most common cause of system crashes. We have developed a new OS component, called a Shadow Driver, that transparently recovers a failed device driver in a simple and straightforward way.

• Simultaneous Multithreading ("Hyper-threading") : SMT is a processor architecture that executes multiple instructions from multiple threads each cycle. Intel has included SMT support on its Pentium-4 processors (called "Hyper-threading"), and IBM supports SMT on its Power-5 CPU.

Hank is author of two books and numerous papers on computer systems design. Among his publications are over a dozen award papers, including 8 from the top operating systems conferences (SOSP and OSDI). He is former chair of ACM SIGOPS (the Special Interest Group on Operating Systems), former program chair of the ACM Symposium on Operating Systems Principles (SOSP), the ACM Conference on Arhictectural Support for Programming Languages and Operating Systems (ASPLOS), and the IEEE Workshop on Hot Topics in Operating Systems (HOTOS). He is a member of the Technical Advisory Boards of Isilon Systems, Zillow.com, and Madrona Venture Group. He is a co-founder of Skytap and was a co-founder of Performant, Inc. (acquired by Mercury in 2003). Hank is a Fellow of the ACM (Association for Computing Machinery), a Fellow of the IEEE (Institute for Electrical and Electronics Engineers), and recipient of a Fulbright Research Scholar Award. He was deeply involved with the architects (LMN) and contractors (Mortenson Construction) for the Paul G. Allen Center for Computer Science & Engineering, and is art curator for the Allen Center art collection (see article in University Week).

Twenty-two Ph.D. and seventeen Master's students have survived Levy's supervision; the Ph.D. students have escaped to academic positions or major research labs. When not glued to his workstation, Hank can usually be found skiing, biking, playing tennis, helping to lead the department's infamous softball team (the Smiling Potatoes of Death), or sampling desserts at one of Seattle's many dessert parlors.

The out-of-print 1984 book on Capability-Based Computer Systems -- a survey and description of early object-based and capability-based processors and operating systems, is now available on line here.

Current students

Roxana Geambasu
John Hseih
Mark Zbikowski

Some of my former PhD students

Some Example Publications

• Vanish: Increasing Data Privacy with Self-Destructing Data, Roxana Geambasu, Tadayoshi Kohno, Amit A. Levy, and Henry M. Levy. Proc. of the 18th USENIX Security Symposium, August 2009 (award paper).

• Flashproxy: Transparently Enabling Rich Web Content via Remote Execution, Alexander Moshchuk, Steven D. Gribble, and Henry M. Levy. Proc. of the 6th International Conference on Mobile Systems, Applications, and Services (MobiSys), June 2008 (honorable mention paper).

• Organizing and Sharing Distributed Personal Web-Service Data. Roxana Geambasu, Cherie Cheung, Alexander Moshchuk, Steven D. Gribble, and Henry M. Levy. Proc. of the 17th International World Wide Web Conference (WWW 2008), April 2008.

• SpyProxy: Execution-based Detection of Malicious Web Content. Alexander Moshchuk, Tanya Bragin, Damien Deville, Steven D. Gribble, and Henry M. Levy. Proc. of the 16th Usenix Security Symposium, August 2007.

• Homeviews: Peer-to-Peer Middleware for Personal Data Sharing Applications. Roxana Geambasu, Magdalena Balazinska, Steven D. Gribble, and Henry M. Levy. Proc. of the ACM International Conference on Management of Data (SIGMOD), June 2007.

• Recovering Device Drivers. Michael Swift, Muthukaruppan Annamalai, Brian N. Bershad, and Henry M. Levy. ACM Trans. on Computer Systems 24(4), November 2006. (Extended version of paper that appeared in Proc. of the 6th ACM/USENIX Symposium on Operating Systems Design and Implementation (OSDI), December 2004 (award paper).)

• A Safety-Oriented Platform for Web Applications. Richard S. Cox, Jacob Gorm Hansen, Steven D. Gribble, and Henry M. Levy. Proc. of the 2006 IEEE Symposium on Security and Privacy, Oakland, CA, May 2006.

• A Crawler-Based Study of Spyware on the Web. Alexander Moshchuk, Tanya Bragin, Steven D. Gribble, and Henry M. Levy. Proc. of the 13th Annual Network and Distributed System Security Symposium (NDSS '06), February 2006.

• Improving the Reliability of Internet Paths with One-hop Source Routing. Krishna P. Gummadi, Harsha V. Madhyastha, Steven D. Gribble, Henry M. Levy, and David Wetherall. Proc. of the Sixth ACM/USENIX Symposium on Operating Systems Design and Implementation (OSDI), December 2004.

• Measurement and Analysis of Spyware in a University Environment. Stefan Saroiu, Steven D. Gribble, and Henry M. Levy. Proc. of the First Symposium on Networked Systems Design and Implementation (NSDI), March 2004.

• Improving the Reliability of Commodity Operating Systems. Michael M. Swift, Brian N. Bershad, and Henry M. Levy. ACM Trans. on Computer Systems 22(4), November 2004. (Extended version of paper that appeared in Proc. of the 19th ACM Symposium on Operating Systems Principles, October 2003 (award paper).)

• Measurement, Modeling, and Analysis of a Peer-to-Peer File-Sharing Workload. Krishna P. Gummadi, Richard J. Dunn, Stefan Saroiu, Steven D. Gribble, Henry M. Levy, and John Zahorjan. Proc. of the 19th ACM Symposium on Operating Systems Principles, October 2003.

• An Analysis of Internet Content Delivery Systems. Stefan Saroiu, Krishna P. Gummadi, Richard J. Dunn, Steven D. Gribble, and Henry M. Levy. Proc. of the 5th Symposium on Operating Systems Design and Implementation (OSDI), December 2002. (award paper)

• Measurement and Analysis of a Streaming-Media Workload. Maureen Chesire, Alec Wolman, Geoffrey Voelker, and Henry Levy. Proc. of the 3rd USENIX Symp. on Internet Technology and Systems (USITS), March 2001. (award paper)

• Manageability, Availability and Performance in Porcupine: A Highly Scalable Cluster-Based Mail Service. Yasushi Saito, Brian Bershad, and Henry Levy. ACM Trans. on Computer Systems 18(3), August 2000. (This is an extended version of the paper that appeared in the Proc. of the 17th ACM Symp. on Operating Systems Principles, December 1999.) (award paper)

• On the scale and performance of cooperative Web proxy caching. Alec Wolman, Geoff Voelker, Nitin Sharma, Neal Cardwell, Anna Karlin, and Henry Levy. Proc. of the 17th ACM Symp. on Operating Systems Principles, December 1999.

• Exploiting Choice: Instruction Fetch and Issue on an Implementable Simultaneous Multithreading Processor. Dean Tullsen, Susan Eggers, Joel Emer, Henry Levy, Jack Lo, and Rebecca Stamm. In Proc. of the 23rd International Symposium on Computer Architecture, May 1996.

• Simultaneous Multithreading: Maximizing On-Chip Parallelism. Dean Tullsen, Susan Eggers, and Henry Levy. In. Proc. of the 22nd Annual International Symposium on Computer Architecture, June 1995.

• Sharing and Protection in a Single-Address-Space Operating System. Jeffrey S. Chase, Henry M. Levy, Michael J. Feeley, and Edward D. Lazowska. ACM Transactions on Computer Systems, 12(4), November 1994.