SAPAN BHATIA
POSTDOC / CS.PRINCETON.EDU

Coordinates

35, Olden Street
Princeton University
Princeton, NJ
sapanb @ cs . princeton . edu
WWW:    http://www.cs.princeton.edu/~sapanb/
Office:  318B

Lightweight, High-Resolution Monitoring for Troubleshooting Production Systems
Sapan Bhatia, Abhishek Kumar, Marc Fiuczynski and Larry Peterson. OSDI '08. To appear.

Remote Specialization for Efficient Embedded Operating Systems.
Sapan Bhatia, Charles Consel and Calton Pu. ACM Transactions on Programming Languages and Systems (TOPLAS). August 2008.

Research

• VINI

  VINI is a virtual network infrastructure that allows network researchers to evaluate their protocols and services in a realistic environment that also provides a high degree of control over network conditions. We are building on native virtualization support in the Linux kernel to make virtual networking in VINI efficient and robust.
  
  Lightweight OS support for a scalable and robust virtual network infrastructure. Sapan Bhatia, Marc Fiuczynski, Andy Bavier and Larry Peterson. Poster session at NSDI'07. Extended abstract. Poster. An extended version appeared at ROADS'07.
  

• Chopstix
  

  Chopstix is diagnostic tool for intermittent problems on production systems that are hard to diagnose. Most people who have maintained such systems can relate to such problems. Chopstix collects system-wide profiles of high-frequency events such as process scheduling, memory allocation and page mapping based on the belief that these events are sensitive to changes in system behavior. Thus, the profiles can be reconstructed offline to understand problems, which are basically unexpected deviations in the system's behavior. Chopstix collects partial stack traces for every unique event, making it possible to trace a problem to its underlying root cause. Chopstix is part of the PlanetLab 4.2 release and will be made available as a public debugging service shortly.

• Misc

  Selective and Non-Selective Autophagic Degradation of Mitochondria in Yeast. Ingrid Kissova, Benedicte Salin, Jacques Schaeffer, Sapan Bhatia, Stephen Manon and Nadine Camougrand. Autophagy journal. Vol 3/Issue 4. July/August 2007.
  

For my old publications, please visit here.

Development

patchdep
Patch dependency analyzer. You specify the set of patches that you would like in your kernel, along with the set that you don't support and patchdep will compute the minimal subset of patches that you need along with the conflicts you need to resolve.



PlanetFlow2
PlanetFlow2 is the new and upcoming version of PlanetFlow, which is PlanetLab's Netflow collection and query system. It uses an extended version of fprobe (http://fprobe.sf.net) to collect and store data, and silk-tools to archive and query it.
PlanetFlow2 also has a WIP monitoring interface: PlanetFlow Monitor (pfmon).

vsys
vsys is to PlanetLab, what the /sys directory is to a Linux server. It is a mechanism to export privileged scripts to PlanetLab slices. vsys has a backend directory, located in root context on the node, and a frontend directory, which appears in the context of a slice. Scripts stored at the backend appear at the frontend as FIFO pipes, which slices can use to invoke and manage the scripts. vsys is written in ocaml and can be checked out of the Planet-Lab CVS.

shortbridge
We found that bridging ethernet devices has a high overhead and can reduce the throughput of forwarding experiments by up to a factor of 5. Shortbridge (abbr. for 'short-circuit bridge') overcomes this problem for pairs of devices, by cross-wiring the corresponding device objects. Implemented as a kernel module + patch for linux 2.6.20. New It looks like the macvlan module for Linux, released recently, subsumes the above functionality, and will probably replace shortbridge.

Links

Here's a nice document proofreading service run by my friends.

Pain

I'm going to start collecting bugs that I have a hard time finding, in the hope that somebody looking for the same information will find it.
Inotify sometimes misses events because it coalesces them