Weekly ReportStart learning GPU

Ph.D. Student: Leo Leedate: Sep. 18, 2009

Outline

• References

• CUDA

• Work plan

Outline

• References

• CUDA

• Work plan

References

Frequent itemset mining on graphics

• Introduction– Two representative algorithms: Apriori and FP-growth;

• FP-growth were generally faster than Apriori;• Apriori-borgelt was slightly faster when the support was high;

– No prior work focuses on studying the GPU acceleration for FIM algorithms.

– Challenge: the data structure is not aligned and access patterns are not regular (pointer-chasing).

Frequent itemset mining on graphics

• Background and related work-GPGPU

– The parallel primitives [19] are a small set of common operations exploiting the architectural features of GPUs. We utilize map, reduce, and prefix sum primitives in our two FIM implementations.

– Improvement - Memory optimizations: • Local memory optimization for temporal locality• Coalesced access optimization of device memory for spatial locality• The built-in vector data type to reduce the number of memory access.

– Difference• we study the GPU acceleration of Apriori for FIM, which incurs much more

complex control fows and memory accesses than performing database joins or maintaining quantiles from data streams.

Frequent itemset mining on graphics

• Implementation

Frequent itemset mining on graphics

• Implementation

Frequent itemset mining on graphics

• Implementation-Pure Bitmap Implementation

Frequent itemset mining on graphics

• Implementation-PBIGiven m frequent (K ¡1)-itemsets, and n items. In order to check whether one (K ¡ 1)-itemset is frequent, we need to access (logm*(n/128)*16) bytes of data, where logm is the cost of performing a binary search, and (n/128)*16 is the size of a row (in bytes) in the bitmap of (K¡1)-itemsets. Typically, if m = 10000 and n = 10000, we need to access about 16 KB for checking only one (K ¡ 1)-subset. This problem in our pure bitmap- based solution triggers us to consider adopting another data structure in the Candidate Generation procedure in the presence of a large number of items.

Frequent itemset mining on graphics

• Implementation-Trie based ImplemetationThe candidate generation based on trie traversal is implemented on the CPU. This decision is based on the fact that, the trie is an irregular structure and difficult to share among SIMD threads. Thus, we store the trie representing itemsets in the CPU memory, and the bitmap representation of transactions in the GPU device memory.

Frequent itemset mining on graphics

• Implementation-TBI

Frequent itemset mining on graphics

• Experiments

Frequent itemset mining on graphics

• Experiments

Frequent itemset mining on graphics

• Results

Frequent itemset mining on graphics

• Results

Frequent itemset mining on graphics

• Results

Frequent itemset mining on graphics

• Results

Outline

• References

• CUDA

• Work plan

CUDA

• Review the code of K-means – CPU: 1101 S (10 S)– GPU: still need debug, no results right now

Outline

• References

• CUDA

• Work plan

Work Plan

• Summary this month

• Make plan for next month

• Try to implement a data mining algorithm

• Homework

References

Key words Google scholar ACM portal

GPU decision tree 2,230 222

GPU k-means 388 184

GPU SVM 416 27

GPU Apriori 1,980 11

GPU Expectation Maximization

266 24

GPU PageRank 4,260 5

GPU AdaBoost 113 9

GPU k-nn 314 20

GPU Naive Bayes 104 2 (false positive)

GPU CART 1,040 3 (false positive)

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