3,101 research outputs found
GPU LSM: A Dynamic Dictionary Data Structure for the GPU
We develop a dynamic dictionary data structure for the GPU, supporting fast
insertions and deletions, based on the Log Structured Merge tree (LSM). Our
implementation on an NVIDIA K40c GPU has an average update (insertion or
deletion) rate of 225 M elements/s, 13.5x faster than merging items into a
sorted array. The GPU LSM supports the retrieval operations of lookup, count,
and range query operations with an average rate of 75 M, 32 M and 23 M
queries/s respectively. The trade-off for the dynamic updates is that the
sorted array is almost twice as fast on retrievals. We believe that our GPU LSM
is the first dynamic general-purpose dictionary data structure for the GPU.Comment: 11 pages, accepted to appear on the Proceedings of IEEE International
Parallel and Distributed Processing Symposium (IPDPS'18
Shared Arrangements: practical inter-query sharing for streaming dataflows
Current systems for data-parallel, incremental processing and view
maintenance over high-rate streams isolate the execution of independent
queries. This creates unwanted redundancy and overhead in the presence of
concurrent incrementally maintained queries: each query must independently
maintain the same indexed state over the same input streams, and new queries
must build this state from scratch before they can begin to emit their first
results. This paper introduces shared arrangements: indexed views of maintained
state that allow concurrent queries to reuse the same in-memory state without
compromising data-parallel performance and scaling. We implement shared
arrangements in a modern stream processor and show order-of-magnitude
improvements in query response time and resource consumption for interactive
queries against high-throughput streams, while also significantly improving
performance in other domains including business analytics, graph processing,
and program analysis
Optimal Hierarchical Layouts for Cache-Oblivious Search Trees
This paper proposes a general framework for generating cache-oblivious
layouts for binary search trees. A cache-oblivious layout attempts to minimize
cache misses on any hierarchical memory, independent of the number of memory
levels and attributes at each level such as cache size, line size, and
replacement policy. Recursively partitioning a tree into contiguous subtrees
and prescribing an ordering amongst the subtrees, Hierarchical Layouts
generalize many commonly used layouts for trees such as in-order, pre-order and
breadth-first. They also generalize the various flavors of the van Emde Boas
layout, which have previously been used as cache-oblivious layouts.
Hierarchical Layouts thus unify all previous attempts at deriving layouts for
search trees.
The paper then derives a new locality measure (the Weighted Edge Product)
that mimics the probability of cache misses at multiple levels, and shows that
layouts that reduce this measure perform better. We analyze the various degrees
of freedom in the construction of Hierarchical Layouts, and investigate the
relative effect of each of these decisions in the construction of
cache-oblivious layouts. Optimizing the Weighted Edge Product for complete
binary search trees, we introduce the MinWEP layout, and show that it
outperforms previously used cache-oblivious layouts by almost 20%.Comment: Extended version with proofs added to the appendi
The Logarithmic Funnel Heap: A Statistically Self-Similar Priority Queue
The present work contains the design and analysis of a statistically
self-similar data structure using linear space and supporting the operations,
insert, search, remove, increase-key and decrease-key for a deterministic
priority queue in expected O(1) time. Extract-max runs in O(log N) time. The
depth of the data structure is at most log* N. On the highest level, each
element acts as the entrance of a discrete, log* N-level funnel with a
logarithmically decreasing stem diameter, where the stem diameter denotes a
metric for the expected number of items maintained on a given level.Comment: 14 pages, 4 figure
MDS-WLAN: Maximal Data Security in WLAN for Resisting Potential Threats
The utmost security standards over Wireless Local Area Network (WLAN) are still an unsolved answer in research community as well as among the commercial users. There are various prior attempts in proposing security of WLAN that lacks focus on access point and is found to be quite complex implementation of cryptography. The proposed paper presents a novel, simple, and yet robust technique called as MDS-WLAN i.e. maximal data security in WLAN. The system is evaluated over laboratory prototype and mitigation measures are drawn for resisting wormhole attack, Sybil attack, and rogue access point issue in WLAN. The outcome of the MDS is compared with conventional AES and SHA that shows optimal communication performance and highest data security
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