28,561 research outputs found
Linear Memory Networks
Recurrent neural networks can learn complex transduction problems that
require maintaining and actively exploiting a memory of their inputs. Such
models traditionally consider memory and input-output functionalities
indissolubly entangled. We introduce a novel recurrent architecture based on
the conceptual separation between the functional input-output transformation
and the memory mechanism, showing how they can be implemented through different
neural components. By building on such conceptualization, we introduce the
Linear Memory Network, a recurrent model comprising a feedforward neural
network, realizing the non-linear functional transformation, and a linear
autoencoder for sequences, implementing the memory component. The resulting
architecture can be efficiently trained by building on closed-form solutions to
linear optimization problems. Further, by exploiting equivalence results
between feedforward and recurrent neural networks we devise a pretraining
schema for the proposed architecture. Experiments on polyphonic music datasets
show competitive results against gated recurrent networks and other state of
the art models
Improving the Performance and Endurance of Persistent Memory with Loose-Ordering Consistency
Persistent memory provides high-performance data persistence at main memory.
Memory writes need to be performed in strict order to satisfy storage
consistency requirements and enable correct recovery from system crashes.
Unfortunately, adhering to such a strict order significantly degrades system
performance and persistent memory endurance. This paper introduces a new
mechanism, Loose-Ordering Consistency (LOC), that satisfies the ordering
requirements at significantly lower performance and endurance loss. LOC
consists of two key techniques. First, Eager Commit eliminates the need to
perform a persistent commit record write within a transaction. We do so by
ensuring that we can determine the status of all committed transactions during
recovery by storing necessary metadata information statically with blocks of
data written to memory. Second, Speculative Persistence relaxes the write
ordering between transactions by allowing writes to be speculatively written to
persistent memory. A speculative write is made visible to software only after
its associated transaction commits. To enable this, our mechanism supports the
tracking of committed transaction ID and multi-versioning in the CPU cache. Our
evaluations show that LOC reduces the average performance overhead of memory
persistence from 66.9% to 34.9% and the memory write traffic overhead from
17.1% to 3.4% on a variety of workloads.Comment: This paper has been accepted by IEEE Transactions on Parallel and
Distributed System
bdbms -- A Database Management System for Biological Data
Biologists are increasingly using databases for storing and managing their
data. Biological databases typically consist of a mixture of raw data,
metadata, sequences, annotations, and related data obtained from various
sources. Current database technology lacks several functionalities that are
needed by biological databases. In this paper, we introduce bdbms, an
extensible prototype database management system for supporting biological data.
bdbms extends the functionalities of current DBMSs to include: (1) Annotation
and provenance management including storage, indexing, manipulation, and
querying of annotation and provenance as first class objects in bdbms, (2)
Local dependency tracking to track the dependencies and derivations among data
items, (3) Update authorization to support data curation via content-based
authorization, in contrast to identity-based authorization, and (4) New access
methods and their supporting operators that support pattern matching on various
types of compressed biological data types. This paper presents the design of
bdbms along with the techniques proposed to support these functionalities
including an extension to SQL. We also outline some open issues in building
bdbms.Comment: This article is published under a Creative Commons License Agreement
(http://creativecommons.org/licenses/by/2.5/.) You may copy, distribute,
display, and perform the work, make derivative works and make commercial use
of the work, but, you must attribute the work to the author and CIDR 2007.
3rd Biennial Conference on Innovative Data Systems Research (CIDR) January
710, 2007, Asilomar, California, US
Accelerating sequential programs using FastFlow and self-offloading
FastFlow is a programming environment specifically targeting cache-coherent
shared-memory multi-cores. FastFlow is implemented as a stack of C++ template
libraries built on top of lock-free (fence-free) synchronization mechanisms. In
this paper we present a further evolution of FastFlow enabling programmers to
offload part of their workload on a dynamically created software accelerator
running on unused CPUs. The offloaded function can be easily derived from
pre-existing sequential code. We emphasize in particular the effective
trade-off between human productivity and execution efficiency of the approach.Comment: 17 pages + cove
Improving the scalability of parallel N-body applications with an event driven constraint based execution model
The scalability and efficiency of graph applications are significantly
constrained by conventional systems and their supporting programming models.
Technology trends like multicore, manycore, and heterogeneous system
architectures are introducing further challenges and possibilities for emerging
application domains such as graph applications. This paper explores the space
of effective parallel execution of ephemeral graphs that are dynamically
generated using the Barnes-Hut algorithm to exemplify dynamic workloads. The
workloads are expressed using the semantics of an Exascale computing execution
model called ParalleX. For comparison, results using conventional execution
model semantics are also presented. We find improved load balancing during
runtime and automatic parallelism discovery improving efficiency using the
advanced semantics for Exascale computing.Comment: 11 figure
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