The PerfNet group works primarily in the following areas of performance and networks: Software and Distributed Systems, and Wireless Networks. Recently, we have also started working in the area of self-tuning systems.

• Software and Distributed Systems Performance: On-line Web-based systems of today are getting increasingly complex, with hundreds of hardware, software and networking resources involved in providing a single service. We are working on several aspects of this problem, all of which need to be solved in order to make these systems self-tuning, self-configuring and ultimately, fully "autonomic":
  • Distributed Systems QoS Modeling Tool: Here, we have aimed to develop methods and tools that can capture all aspects of software and hardware interactions, to create a detailed performance model of a complex distributed system, so that important performance characteristics such as response time of a certain service, or bottlenecks in the server systems can be found easily. We have developed new analytical methods to capture various behaviors, and have developed a simulator that aims to model behaviors that cannot be solved analytically. Currently, Rukma Verlekar (M. Tech. - 3) and Manuj Gupta (M. Tech. - 2) are working on this project. Future work involves developing more sophisticated analytical models and ading more features to the simulator. This work is funded by a grant from the Ministry of Human Resource Development, Govt. of India.
  • Automated Capacity Analysis and Profiling Tool: Since such a modeling tool would require a fairly detailed profile of the behavior of the distributed system, we have developed a tool [S2] that can profile the resource consumption by server components (e.g. CPU time required on a particular server by a particular transaction). Shrirang (M. Tech. - 2) is continuing development on this tool, and Rishi Gupta (DD - 5), is making it work on the .NET/J2EE platform. Related work in profiling the topology of distributed services is being carried out by Prof. Umesh Bellur. Further work in this involves adding more "intelligence" features to the tools. This joint work is funded by a grant from Intel Corporation, USA.
  • DETAILS http://aloha.cse.iitb.ac.in/wiki/doku.php?id=softperf:autoprof:home
  • DETAILS of Topology Related Work under Prof. Umesh Bellur

http://aloha.cse.iitb.ac.in/wiki/doku.php?id=softperf:autoprof:home#topology-related-work-prof.-umesh-bellur

• Overload/Admission Control of Web Servers: Web servers (and other servers) can show severely degraded performance when offered traffic exceeds the capacity. This problem can and should be solved by building in explicit mechanisms which improve performance during overload ([S3], joint work with Prof. D. Manjunath), or avoiding overload (admission control). We are studying this problem by modeling it analytically as well as by implementing test-beds and measuring performance. Vipul Mathur (Research Scholar) and Rukma Verlekar (M. Tech. - 3) are currently involved in this work. This work is funded by a grant from Amazon India Development Center, Bangalore, India.
• Advanced Models and Studies of Software Systems: While we develop methods that model software at a high level, we have also studied and modeled some aspects of software behaviour in detail. Specifically, we have developed a “complexity-aware” model of software servers [S4], and carried out a measurement study of the performance of the Linux TCP/IP stack [S1] (work funded by UNM Systems, Inc.). Shishir Agarwal (Alumni) worked on performance-based availability models of software systems.
• Wireless Networks: The IEEE 802.11 family of protocols has gained immense popularity over the last few years. Several performance-related aspects of these protocols are not yet understood fully. We been worked on two separate projects in this area:
• QoS and Performance: Preetam Patil (Research Scholar) has studied the sizing problem for the 802.11 WLAN [W2] and Kiran K. Gavini (M. Tech., 2005) worked on the admission control problem for 802.11e WLAN [W1] (jointly with Prof. Sridhar Iyer). Ajay Singh (Alumni) continued to work on the admission control problem. We are now embarking on a major project, where we plan to implement a large WLAN test-bed on which we will carry out multimedia traffic experiments. The focus of this project is to make things work. We have to work with whatever equipment is currently available, and demonstrate the capability of carrying high quality voice and video conversations. This will involve solving admission control problems, and handoffs for implementing mobility, Preetam Patil and Yogesh Powar (M. Tech - 2), are currently involved in this work. This work is funded by a grant from the Ministry of Human Resource Development, Govt. of India.
• Location Determination: We have also developed a highly accurate WLAN-based location determination system [WT2]. Several extensions need to be made to this work: accuracy needs to be improved, and we need to make it work for fast-moving devices. An interesting service also needs to be built using the location determination.

(See Publications for the cited references.)