18,234 research outputs found
Dynamic Parameter Allocation in Parameter Servers
To keep up with increasing dataset sizes and model complexity, distributed
training has become a necessity for large machine learning tasks. Parameter
servers ease the implementation of distributed parameter management---a key
concern in distributed training---, but can induce severe communication
overhead. To reduce communication overhead, distributed machine learning
algorithms use techniques to increase parameter access locality (PAL),
achieving up to linear speed-ups. We found that existing parameter servers
provide only limited support for PAL techniques, however, and therefore prevent
efficient training. In this paper, we explore whether and to what extent PAL
techniques can be supported, and whether such support is beneficial. We propose
to integrate dynamic parameter allocation into parameter servers, describe an
efficient implementation of such a parameter server called Lapse, and
experimentally compare its performance to existing parameter servers across a
number of machine learning tasks. We found that Lapse provides near-linear
scaling and can be orders of magnitude faster than existing parameter servers
LINE: Large-scale Information Network Embedding
This paper studies the problem of embedding very large information networks
into low-dimensional vector spaces, which is useful in many tasks such as
visualization, node classification, and link prediction. Most existing graph
embedding methods do not scale for real world information networks which
usually contain millions of nodes. In this paper, we propose a novel network
embedding method called the "LINE," which is suitable for arbitrary types of
information networks: undirected, directed, and/or weighted. The method
optimizes a carefully designed objective function that preserves both the local
and global network structures. An edge-sampling algorithm is proposed that
addresses the limitation of the classical stochastic gradient descent and
improves both the effectiveness and the efficiency of the inference. Empirical
experiments prove the effectiveness of the LINE on a variety of real-world
information networks, including language networks, social networks, and
citation networks. The algorithm is very efficient, which is able to learn the
embedding of a network with millions of vertices and billions of edges in a few
hours on a typical single machine. The source code of the LINE is available
online.Comment: WWW 201
Distributed Low-rank Subspace Segmentation
Vision problems ranging from image clustering to motion segmentation to
semi-supervised learning can naturally be framed as subspace segmentation
problems, in which one aims to recover multiple low-dimensional subspaces from
noisy and corrupted input data. Low-Rank Representation (LRR), a convex
formulation of the subspace segmentation problem, is provably and empirically
accurate on small problems but does not scale to the massive sizes of modern
vision datasets. Moreover, past work aimed at scaling up low-rank matrix
factorization is not applicable to LRR given its non-decomposable constraints.
In this work, we propose a novel divide-and-conquer algorithm for large-scale
subspace segmentation that can cope with LRR's non-decomposable constraints and
maintains LRR's strong recovery guarantees. This has immediate implications for
the scalability of subspace segmentation, which we demonstrate on a benchmark
face recognition dataset and in simulations. We then introduce novel
applications of LRR-based subspace segmentation to large-scale semi-supervised
learning for multimedia event detection, concept detection, and image tagging.
In each case, we obtain state-of-the-art results and order-of-magnitude speed
ups
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