FREERIDE: System Support for High Performance Data Mining Ruoming Jin Leo Glimcher Xuan Zhang Ge...
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Transcript of FREERIDE: System Support for High Performance Data Mining Ruoming Jin Leo Glimcher Xuan Zhang Ge...
FREERIDE: System Support for High Performance Data Mining
Ruoming Jin Leo Glimcher Xuan Zhang
Ge Yang Gagan Agrawal
Department of Computer and Information SciencesOhio State University
Motivation: Data Mining Problem Datasets available for mining
are often large Our understanding of what
algorithms and parameters will give desired insights is limited
Time required for creating scalable implementations of different algorithms and running them with different parameters on large datasets slows down the data mining process
Project Overview
FREERIDE (Framework for Rapid Implementation of datamining engines) as the base system
Demonstrated for a variety of standard mining algorithms
FREERIDE offers: The ability to rapidly prototype a high-performance mining
implementation Distributed memory parallelization Shared memory parallelization Ability to process large and disk-resident datasets Only modest modifications to a sequential implementation for
the above three
Key Observation from Mining Algorithms
Popular algorithms have a common canonical loop
Can be used as the basis for supporting a common middleware
While( ) {
forall( data instances d) {
I = process(d)
R(I) = R(I) op d
}
…….
}
Shared Memory Parallelization Techniques
Full Replication: create a copy of the reduction object for each thread
Full Locking: associate a lock with each element
Optimized Full Locking: put the element and corresponding lock on the same cache block
Fixed Locking: use a fixed number of locks Cache Sensitive Locking: one lock for all
elements in a cache block
Memory Layout for Various Locking Schemes
Full Locking Fixed Locking
Optimized Full Locking Cache-Sensitive Locking
Lock Reduction Element
Trade-offs between Techniques
Memory requirements: high memory requirements can cause memory thrashing
Contention: if the number of reduction elements is small, contention for locks can be a significant factor
Coherence cache misses and false sharing: more likely with a small number of reduction elements
Combining Shared Memory and Distributed Memory Parallelization
Distributed memory parallelization by replication of reduction object
Naturally combines with full replication on shared memory
For locking with non-trivial memory layouts, two options
Communicate locks also Copy reduction elements to a separate buffer
Apriori Association Mining
Relative Performance of Full Replication, Optimized Full Locking and Cache-Sensitive Locking
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4000060000
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0.10% 0.05% 0.03% 0.02%
Support Levels
Tim
e(s)
fr
ofl
csl
500MB dataset, N2000,L20, 4 threads
K-means Shared Memory Parallelization
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full repl
opt full locks
cache sens.Locks
Performance on Cluster of SMPs
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1 node 2nodes
4nodes
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1 thread 2 threads 3 threads
Apriori Association Mining
Results from EM Clustering Algorithm
EM is a popular data mining algorithm
Can we parallelize it using the same support that worked for other clustering algo (k-means) and algo for other mining tasks
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1 thread 2 threads 3 threads 4 threads
Results from FP-tree
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1 thread 2 threads 3 threads
FPtree: 800 MB dataset 20 frequent itemsets
A Case Study: Decision Tree Construction
• Question: can we parallelize decision tree construction using the same framework ?
• Most existing parallel algorithms have a fairly different structure (sorting, writing back …)
• Being able to support decision tree construction will significantly add to the usefulness of the framework
Approach
Implemented RainForest framework (Gehrke) Currently focus on RF-read Overview of the algorithm
While the stop condition not satisfied read the data build the AVC-group for nodes choose the splitting attributes to split nodes select a new set of node to process as long as the main
memory could hold it
Parallelization Strategies
Pure approach: only apply one of full replication, optimized full locking and cache-sensitive locking
Vertical approach: use replication at top levels, locking at lower
Horizontal: use replication for attributes with a small number of distinct values, locking otherwise
Mixed approach: combine the above two
Results
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1 2 4 8
No. of Nodes
Tim
e(s
) fr
ofl
csl
Performance of pure versions, 1.3GB dataset with 32 million records in the training set, function 7, the depth of decision tree = 16.
Results
Combining full replication and full locking
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1 2 4 8
No. of Nodes
Tim
e(s
) horizontal
vertical
mixed
Results
Combining full replication and cache-sensitive locking
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1 2 4 8
No. of Nodes
Tim
e(s
) horizontal
vertical
mixed
Combining Distributed Memory and Shared Memory Parallelization for Decision Tree
The key problem: large size of AVC groups means very high communication volume
Results in very limited speedups Can we modify the algorithm to reduce
communication volume ?
SPIES On (a) FREERIDE Developed a new
communication efficient decision tree construction algorithm – Statistical Pruning of Intervals for Enhanced Scalability (SPIES)
Combines RainForest with statistical pruning of intervals of numerical attributes to reduce memory requirements and communication volume
Does not require sorting of data, or partitioning and writing-back of records
Paper in SDM regular program
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1node
8nodes
1thread 2threads 3threads
Applying FREERIDE for Scientific Data Mining
Joint work with Machiraju and Parthasarathy
Focusing on feature extraction, tracking, and mining approach developed by Machiraju et al.
A feature is a region of interest in a dataset
A suite of algorithms for extracting and tracking features
Summary
Demonstrated a common framework for parallelization of a wide range of mining algos
Association mining – apriori and fp-tree Clustering – k-means and EM Decision tree construction Nearest neighbor search
Both shared memory and distributed memory parallelism
A number of advantages Ease parallelization Support higher-level interfaces