Brief Announcement: Improved Approximation Algorithms for Scheduling Co-Flows

Co-flow scheduling is a recent networking abstraction introduced to capture application-level communication patterns in datacenters. In this paper, we consider the offline co-flow scheduling problem with release times to minimize the total weighted completion time. Recently, Qiu, Stein and Zhong (SPAA, 2015) obtained the first constant approximation algorithms for this problem with a deterministic 67/3-approximation and a randomized (9 + 16√2)/3 ≅ 16.54-approximation. In this paper, we improve upon their algorithm to yield a deterministic 12-approximation algorithm. For the special case when all release times are zero, we obtain a deterministic 8-approximation and a randomized (3+2√2) ≅ 5.83-approximation.