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Summary: The Impact of False Sharing on Shared Congestion Management
Aditya Akella, Srinivasan Seshan Hari Balakrishnan
Carnegie Mellon University Massachusetts Institute of Technology
Abstract
Several recent proposals for sharing congestion information
across concurrent flows between end-systems overlook an impor-
tant problem: two or more flows sharing congestion state may in
fact not share the same bottleneck. In this paper, we categorize the
origins of this false sharing into two distinct cases: (i) networks
with QoS enhancements such as differentiated services, where a
flow classifier segregates flows into different queues, and (ii) net-
works with path diversity where different flows to the same des-
tination address are routed differently. We evaluate the impact of
false sharing on flow performance and investigate how false shar-
ing can be detected by a sender. We discuss how a sender must re-
spond upon detecting false sharing. Our results show that persis-
tent overload can be avoided with window-based congestion con-
trol even for extreme false sharing, but higher bandwidth flows run
at a slower rate. We find that delay and reordering statistics can
be used to develop robust detectors of false sharing and are supe-
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