Webinar Parimal Parag: "Low latency scheduling of replicated fragments on memory constrained servers"

Title: Low latency scheduling of replicated fragments on memory-constrained servers.

Date and timing: 30/06/2022, 3 p.m. --- 4 p.m.

Abstract: We consider the setting of a distributed storage system where a single file is subdivided into smaller fragments of same size which are then replicated with a common replication factor across servers of identical cache size. An incoming file download request is sent to all the servers, and the download is completed whenever the request gathers all the fragments. At each server, we are interested in determining the sequence in which stored fragments should be accessed, such that the mean file download time for a request is minimized. We model the fragment download time as an exponential random variable independent and identically distributed for all fragments across all servers and show that the mean file download time can be lower bounded in terms of the expected number of useful servers summed over all distinct fragment downloads. We show that finding the optimal sequence of accessing the fragments is a Markov decision problem, whose complexity grows exponentially with the number of fragments. We propose heuristic algorithms that determine the sequence of access to the fragments which are empirically shown to perform well.

Bio: Parimal Parag is currently an associate professor in the department of electrical communication engineering at Indian Institute of Science at Bengaluru. He is also a co-convenor of the centre for networked intelligence, a faculty participant at Robert Bosch centre for cyber-physical systems, and a member of the applied probability research group. He was working as senior systems engineer in R&D at ASSIA Inc. from October 2011 to November 2014. He received his B. Tech. and M. Tech. degrees from Indian Institute of Technology Madras in fall 2004; and the PhD degree from Texas A&M University in fall 2011. He was at Stanford University and Los Alamos National Laboratory, in the autumn of 2010 and the summer of 2007, respectively.

He conducts research in network theory, applied probability, optimization methods, and in their applications to distributed systems. His previous work includes performance evaluation, monitoring, and control of large broadband communication systems and networks. His other research interests lie in the areas of game theory, statistical signal processing, queueing theory, information theory, estimation & detection theory, combinatorics, and probability theory.

Website: https://ece.iisc.ac.in/~parimal/