3,773 research outputs found
Coping with dynamic membership, selfishness, and incomplete information: applications of probabilistic analysis and game theory
textThe emergence of large scale distributed computing networks has given increased
prominence to a number of algorithmic concerns, including the need to
handle dynamic membership, selfishness, and incomplete information. In this document,
we outline our explorations into these algorithmic issues.
We first present our results on the analysis of a graph-based coupon collecvi
tor process related to load balancing for networks with dynamic membership. In
addition to extending the study of the coupon collector process, our results imply
load balancing properties of certain distributed hash tables.
Second, we detail our results on worst case payoffs when playing buyersupplier
games, against many selfish, collaborating opponents. We study optimization
over the set of core vectors. We show both positive and negative results on
optimizing over the cores of such games. Furthermore, we introduce and study the
concept of focus point price, which answers the question: If we are constrained to
play in equilibrium, how much can we lose by playing the wrong equilibrium?
Finally, we present our analysis of a revenue management problem with incomplete
information, the online weighted transversal matroid matching problem.
In specific, we present an algorithm that delivers expected revenue within a constant
of optimal in the online setting. Our results use a novel algorithm to generalize
several results known for special cases of transversal matroids.Computer Science
Simple Load Balancing for Distributed Hash Tables
Distributed hash tables have recently become a useful building block for a variety of distributed applications. However, current schemes based upon consistent hashing require both considerable implementation complexity and substantial storage overhead to achieve desired load balancing goals. We argue in this paper that these goals can b e achieved more simply and more cost-effectively. First, we suggest the direct application of the "power of two choices" paradigm, whereby an item is stored at the less loaded of two (or more) random alternatives. We then consider how associating a small constant number of hash values with a key can naturally b e extended to support other load balancing methods, including load-stealing or load-shedding schemes, as well as providing natural fault-tolerance mechanisms
Traffic Management Applications for Stateful SDN Data Plane
The successful OpenFlow approach to Software Defined Networking (SDN) allows
network programmability through a central controller able to orchestrate a set
of dumb switches. However, the simple match/action abstraction of OpenFlow
switches constrains the evolution of the forwarding rules to be fully managed
by the controller. This can be particularly limiting for a number of
applications that are affected by the delay of the slow control path, like
traffic management applications. Some recent proposals are pushing toward an
evolution of the OpenFlow abstraction to enable the evolution of forwarding
policies directly in the data plane based on state machines and local events.
In this paper, we present two traffic management applications that exploit a
stateful data plane and their prototype implementation based on OpenState, an
OpenFlow evolution that we recently proposed.Comment: 6 pages, 9 figure
When Two Choices Are not Enough: Balancing at Scale in Distributed Stream Processing
Carefully balancing load in distributed stream processing systems has a
fundamental impact on execution latency and throughput. Load balancing is
challenging because real-world workloads are skewed: some tuples in the stream
are associated to keys which are significantly more frequent than others. Skew
is remarkably more problematic in large deployments: more workers implies fewer
keys per worker, so it becomes harder to "average out" the cost of hot keys
with cold keys.
We propose a novel load balancing technique that uses a heaving hitter
algorithm to efficiently identify the hottest keys in the stream. These hot
keys are assigned to choices to ensure a balanced load, where is
tuned automatically to minimize the memory and computation cost of operator
replication. The technique works online and does not require the use of routing
tables. Our extensive evaluation shows that our technique can balance
real-world workloads on large deployments, and improve throughput and latency
by and respectively over the previous
state-of-the-art when deployed on Apache Storm.Comment: 12 pages, 14 Figures, this paper is accepted and will be published at
ICDE 201
Optimal Elephant Flow Detection
Monitoring the traffic volumes of elephant flows, including the total byte
count per flow, is a fundamental capability for online network measurements. We
present an asymptotically optimal algorithm for solving this problem in terms
of both space and time complexity. This improves on previous approaches, which
can only count the number of packets in constant time. We evaluate our work on
real packet traces, demonstrating an up to X2.5 speedup compared to the best
alternative.Comment: Accepted to IEEE INFOCOM 201
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