Office: 211 VTKW-2

Office hours: TBD and by appointment

Phone: 540-231-3046

Email: gback@cs.vt.edu

The best way to contact me is by email, but it's okay to drop by anytime my door is open. Send me email if you want to make sure I am there.

Here's my Google calendar - (access may require a Google account)

Current Students

PhD:

• Mehmet Belgin (Co-advised with Dr. Ribbens)
  
• Peng Lu
  

MS:

• Michael Doyle
  
• Amarjyoti Deka
  
• Arif Khokar
  
• Karthik Bacherao
  

I am also advising a number of undergraduate students in undergraduate research projects.

Past Students

Shahrooz Feizabadi. PhD, 2006. now at Retail Decisions, Inc.
Dissertation: Garbage Collection Scheduling for Utility Accrual Real-Time Systems

Tilottama Gaat MS, 2008. now at Schweitzer Engineering.
Thesis: The LibX Edition Builder

Jaishankar Sundaramanan MS, 2008. now at Google.
Thesis: HDPV: Highly Interactive, Faithful, In-Vivo Runtime State Visualization for Software Programs

Nathan Baker. MS, 2007. now at NetApp, Inc.
Thesis: LibX IE: An Internet Explorer Add-On for Direct Library Access

Abhijit Deodhar. MS, 2007. now at NetApp, Inc.
Thesis: COPS: A Framework for Consumer Oriented Proportional share Scheduling

Vijay Kumar Muthukumaraswamy Sivakumar. MS, 2007. now at Microsoft.
Thesis: An Evaluation of the Linux Virtual Memory Manager to Determine Suitability for Runtime Variation of Memory

Prasad Gopal. MS, 2006. now at Google.
Thesis: Top: An Infrastructure for detecting Application-Specific Program Errors by Binary Runtime Instrumentation

Veena Basavaraj. MS, 2006. now at Blackboard, Inc..
Thesis: Optimality of Heuristic Schedulers in Utility Accrual Real-time Scheduling Environments

Research Interests

My research interests lie at the intersection of operating systems and programming languages. Simply put, I'm interested in finding ways to make systems more robust and crash less often.

Current Research

My current research stretches a variety of areas. I am always looking for good students that are interested in all aspects of software systems. My current research involves dynamic runtime checking, static analysis on the programming language side, and real-time scheduling, garbage collection, memory management, network simulation, and parallel programming on the OS side. I am also involved in developed advanced web technology for client- and server-side AJAX applications.

Major ongoing research efforts include

LibX. For an overview, see this talk.

Top and HDPV. See this paper for an overview.

Enhance Thyself - automatic program enhancement. See this paper for an overview.

Virtualization for High-End Computing.

I am looking for GRAs in all three projects.

Past Research

• MJ: I developed MJ, a system which applies meta-level compilation techniques to Java. We have used meta-level compilation as a static analysis tool for finding bugs in large software systems. It found thousands of bugs in the Linux kernel, for instance.

  Of course, in a system written in a weakly-typed language such as C, bugs are a dime a dozen. The challenge in MJ is to apply meta-level compilation to a type-safe language from which simple bugs, such as dangling pointers, have already been eliminated.

• KaffeOS: Single-language runtime systems, in the form of Java virtual machines, are widely deployed platforms for executing untrusted mobile code. These runtimes provide some of the features that operating systems provide: inter-application memory protection and basic system services. They do not, however, provide the ability to isolate applications from each other, or limit their resource consumption. KaffeOS is a Java runtime system that provides these features. The KaffeOS architecture takes many lessons from operating system design, such as the use of a user/kernel boundary, and employs garbage collection techniques, such as write barriers. While KaffeOS has not been released, a successor project, JanosVM is available here.

• DataScript: DataScript is a language to describe and manipulate binary data formats as types. DataScript consists of two components: a constraint-based specification language that uses DataScript types to describe the physical layout of data and a language binding that provides a simple programming interface to script binary data. A DataScript compiler generates Java libraries that are linked with DataScript scripts. A release of the software is available at SourceForge.

• OSKit: The OSKit is a framework and a set of 34 component libraries oriented to operating systems, together with extensive documentation. By providing in a modular way not only most of the infrastructure "grunge" needed by an OS, but also many higher-level components, the project's goal is to lower the barrier to entry to OS R&D and to lower its costs. The OSKit makes it vastly easier to create a new OS, port an existing OS to the x86, or enhance an OS to support a wider range of devices, file system formats, executable formats, or network services. For language researchers and enthusiasts, the OSKit lets them concentrate on the real issues raised by using advanced languages inside operating systems, such as Java, Lisp, Scheme, or ML--- instead of spending six months or years groveling inside ugly code and hardware. The OSKit homepage.

• Kaffe: I was a contributor to the Kaffe project, an open source Java virtual machine.

This semester (Spring 2009)

CS 5565 - Networking Architecture and Protocols.

Courses taught in the past:

• Fall 2008: CS 3204 - Operating Systems.
• Fall 2007: CS 3204 - Operating Systems.
• Fall 2007: CS 5204 - Operating Systems.
• Spring 2007: CS 3204 - Operating Systems.
• Fall 2006: CS 3204 - Operating Systems.
• Spring 2006: CS 3204 - Operating Systems.
• Spring 2006: CS 5565 - Networking Architecture and Protocols.
• Fall 2005: CS 5204 - Operating Systems
• Spring 2005: CS 5565 - Networking Architecture and Protocols.
• Fall 2004: CS 5204 - Operating Systems
• Fall 2002, Summer 2003: CS 143 - Compilers (at Stanford)

I've been Assistant Professor at Virginia Tech since Fall 2004.

I worked as a postdoctoral researcher with Dawson Engler's Meta-Level Compilation Group at Stanford until summer 2004.

I received my PhD from the University of Utah in May 2002. My advisor was Prof. Wilson Hsieh. The topic of my dissertation is "Isolation, Resource Management, and Sharing in the KaffeOS Java Runtime System."

While a graduate student at Utah I was a member of the Flux Group, where I helped design and build the OSKit and Fluke Microkernel projects.

I worked on the Itsy project during a summer internship at the Compaq Western Research Laboratory in 1999.

I studied from 1989 to 1993 at the Humboldt University Berlin and the Technical University Berlin.

While in Berlin I worked for Mummert Consulting, a leading German consulting company in the banking and finance sector. I also interned at the Konrad-Zuse-Zentrum Berlin with the Scientific Visualization group in 1994.

I grew up in Sonneberg, Germany and went to high school at the Goetheschule in Ilmenau.

Godmar Back's Publications

1. "The Pintos Instructional Operating System Kernel." Ben Pfaff, Anthony Romano, and Godmar Back. Proceedings of the 40th ACM Technical Symposium on Computer Science Education (SIGCSE 2009). Chattanooga, TN. March 2009. pp. 453--457.
   
   
2. "A Pattern-based Sparse Matrix Representation for Memory-efficient SMVM Kernels." Mehmet Belgin, Godmar Back, and Calvin J. Ribbens. ICS '09: Proceedings of the 23st annual international conference on Supercomputing. 2009. to appear.
   
   
3. "A Fast JPEG2000 Encoder That Preserves Coding Efficiency: The Split Arithmetic Encoder." Krishnaraj Varma, Hima B. Damecharla, Amy E. Bell, Joan E. Carletta, and Godmar Back. IEEE Transactions on Circuits and Systems I. 55 (11). December 2008. pp. 3711--3722.
   
   
4. "Pattern-based Code Generation for SMVM Kernels." Mehmet Belgin, Godmar Back, and Calvin J. Ribbens. Poster at Supercomputing 2008 (SC'08). November 2008.
   
   
5. "HDPV: interactive, faithful, in-vivo runtime state visualization for C/C++ and Java." Jaishankar Sundararaman and Godmar Back. Proceedings of the 4th ACM Symposium on Software Visualization (SoftVis'08). Ammersee, Germany. September 2008. pp. 47--56. [URL]
   
   
6. "Increasing the visibility of web-based information retrieval systems via client-side mash-ups." Godmar Back and Annette Bailey. Proceedings of the 8th ACM/IEEE-CS Joint Conference on Digital Libraries (JCDL'08). Pittsburgh, PA. June 2008. pp. 418. [URL] Demonstration.
   
   
7. "Program, Enhance Thyself! Demand-Driven Pattern-Oriented Program Enhancement." Eli Tilevich and Godmar Back. Proceedings of the Seventh International Conference on Aspect-Oriented Software Development (AOSD 2008). Brussels, Belgium. April 2008. pp. 13--24. [URL]
   
   
8. "ReplayCache: Exploiting Similarities for Predicting the Future." Ganesh C.N., Jaishankar Sundararaman, Ali R. Butt, and Godmar Back. Poster at 6th USENIX Conference on File and Storage Technologies (FAST 2008). February 2008.
   
   
9. "Application-Specific System Customization on Many-Core Platforms: The VT-ASOS Framework." Godmar Back and Dimitrios S. Nikolopoulos. STMCS: Second Workshop on Software Tools for Multi-Core Systems (STMCS). San Jose, CA. March 2007. [URL]
   
   
10. "Retrieving Known Items with LibX." Annette Bailey and Godmar Back. The Serials Librarian. 53 (4). 2007. pp. 125--140.
    
    
11. "Garbage collection-aware utility accrual scheduling." Shahrooz Feizabadi and Godmar Back. Real-Time Systems. 36 (1-2). 2007. pp. 3--22.
    
    
12. "An operation stacking framework for large ensemble computations." Mehmet Belgin, Calvin J. Ribbens, and Godmar Back. ICS '07: Proceedings of the 21st annual international conference on Supercomputing. Seattle, Washington. New York, NY, USA. 2007. pp. 83--92.
    
    
13. "From Uncertainty to Belief: Inferring the Specification Within." Ted Kremenek, Paul Twohey, Godmar Back, Dawson Engler, and Andrew Ng. accepted to Seventh Symposium on Operating Systems Design and Implementation (OSDI '06). USENIX Association. Seattle, WA. November 2006. pp. 161--176.
    
    
14. "The Distributed Open Network Emulator: Using Relativistic Time for Distributed Scalable Simulation." Craig Bergstrom, Srinidhi Varadarajan, and Godmar Back. Proceedings of the 20th Workshop on Principles of Advanced and Distributed Simulation. Singapore. May 2006. pp. 19--28. [URL]
    
    
15. "Automatic Memory Management in Utility Accrual Scheduling Environments." Shahrooz Feizabadi and Godmar Back. Proceedings of the 9th IEEE International Symposium on Object and component-oriented Real-time distributed Computing (ISORC 2006). IEEE. Gyeongju, South Korea. April 2006. pp. 11--19. [URL]
    
    
16. "LibX - A Firefox Extension for Enhanced Library Access." Annette Bailey and Godmar Back. Library Hi Tech. 24 (2). 2006. pp. 290--304.
    
    
17. "Java Garbage Collection Scheduling in Utility Accrual Scheduling Environments." Shahrooz Feizabadi and Godmar Back. 3rd Workshop on Java Technologies for Real-time and Embedded Systems (JTRES) colocated with OOPSLA 2005. ACM. October 2005. [URL] This workshop paper is superceded by the ISORC-2006 paper..
    
    
18. "The KaffeOS Java Runtime System." Godmar Back and Wilson C Hsieh. ACM Transactions on Programming Languages and Systems. 27 (4). 2005. pp. 583--630. [URL]
    
    
19. "Isolation, Resource Management and Sharing in the KaffeOS Java Runtime System." , Doctoral Dissertation, Godmar Back. University of Utah. 2002. [URL]
    
    
20. "DataScript - A Specification and Scripting Language for Binary Data." Godmar Back. Proceedings of the ACM Conference on Generative Programming and Component Engineering Proceedings (GPCE 2002), published as LNCS 2487. ACM. Pittsburgh, PA. October 2002. pp. 66-77. [URL]
    
    
21. "Reverse-Engineering Instruction Encodings." Wilson C. Hsieh, Dawson R. Engler, and Godmar Back. Proceedings of the USENIX 2001 Annual Technical Conference. USENIX Association. Boston, MA. June 2001. pp. 133--146. [URL]
    
    
22. "Quantifying the Energy Consumption of a Pocket Computer and a Java Virtual Machine." Keith Farkas, Jason Flinn, Godmar Back, Dirk Grunwald, and Jennifer Anderson. Proceedings of SIGMETRICS '00. Santa Clara, CA. June 2000. pp. 252--263. [URL]
    
    
23. "Processes in KaffeOS: Isolation, Resource Management, and Sharing in Java." Godmar Back, Wilson C. Hsieh, and Jay Lepreau. Proceedings of the Fourth Symposium on Operating Systems Design and Implementation (OSDI). USENIX Association. San Diego, CA. October 2000. pp. 333--346. [URL]
    
    
24. "Techniques for the Design of Java Operating Systems." Godmar Back, Patrick Tullmann, Leigh Stoller, Wilson C. Hsieh, and Jay Lepreau. Proceedings of the USENIX 2000 Annual Technical Conference. USENIX Association. San Diego, CA. June 2000. pp. 197--210. [URL]
    
    
25. "Drawing the Red Line in Java." Godmar Back and Wilson C. Hsieh. Proceedings of the Seventh Workshop on Hot Topics in Operating Systems (HOTOS). IEEE Computer Society. Rio Rico, Arizona. March 1999. pp. 116--121. [URL]
    
    
26. "The Flux OSKit: A Substrate for OS and Language Research." Bryan Ford, Godmar Back, Greg Benson, Jay Lepreau, Albert Lin, and Olin Shivers. Proceedings of the 16th ACM Symposium on Operating Systems Principles (SOSP). St. Malo, France. October 1997. pp. 38--51. [URL]
    
    
27. "Formal Methods: A Practical Tool for OS Implementors." Patrick Tullmann, Jeff Turner, John McCorquodale, Jay Lepreau, Ajay Chitturi, and Godmar Back. Proceedings of the Sixth Workshop on Hot Topics in Operating Systems (HOTOS). IEEE Computer Society. Cape Cod, MA. May 1997. pp. 20--25. [URL]
    
    
28. "Microkernels Meet Recursive Virtual Machines." Bryan Ford, Mike Hibler, Jay Lepreau, Patrick Tullmann, Godmar Back, and Stephen Clawson. Proceedings of the Second Symposium on Operating Systems Design and Implementation (OSDI). USENIX Association. Seattle, WA. October 1996. pp. 137--151. [URL]
    
    

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