Bryan Lahartinger

“The Apriori algorithm is a fundamental correlation-based data mining [technique]” “Software implementations of the Aprioiri algorithm utilize…methods...for the support and candidate generation operations” “This paper demonstrates an efficient structure for computing the support of a set of candidates.” “…though the combination of Content-Addessable-Memories (CAM)” “As far as we know, the Aprioiri algorithm has not been studied in any significant way for hardware implementation.” Objective Investigation

To exploit parallelism in hardware to accelerate a bottleneck in the Apriori algorithm with applications specifically to data mining. What is the Aprioiri algorithm? What is the bottleneck? How does hardware acceleration fit into the picture? Objective

Background Apriori Algorithm Apriori bottleneck Bitmapped CAM Implementing Bitmap CAM Analysis of the Approach Results of software comparisons Conclusions Paper Overview

Given transactions consisting of sets: {1,2,3,4}, {2,3,4}, {2,3}, {1,2,4}, {1,2,3,4}, and {2,4} Apriori ItemSupport ItemSupport {1,2}3 {1,3}2 {1,4}3 {2,3}4 {2,4}5 {3,4}3 ItemSupport {1,2,4}3 {2,3,4}3

Each candidate can be addressed to a row of bits Each column represents if a candidate is included in the CAM entry as a candidate Column bits can be summed to form the number of matching candidates Bitmapped CAM

Large LUT in memory Candidate 249 is frequently associated with candidates 1-11 but not 12… Implemented CAM Bitmap

They varied the number of CAM elements to candidates Max CAM blocks of Blocks fit most cases When they didn’t… Solution: Stop adding candidates to the block when full [why?] Analysis of the Approach

VHDL architecture req only 10 cycles per CAM stage (Xilinx 7.2 on Viritex II) Max clock rate 120MHz Used standard datasets Compared software from only 1 hardware platform Used half logic cells per candidates compared to USC FCCM05 (Half FPGA Area?) Results

CAM = awesome VS software = sucks Allows similarities between candidates to be utilized Their previous paper on systolic array architecture of Apriori Algo in hardware would work even better with this improvement An ideal architecture will be constructed/tested with both arch’s combined Conclusions

Pros Intro was unclear at first i.e. NOT about Apriori, but more general applications Reasonable explanation of Apriori and CAM Criticisms

Cons No VHDL implementation details – “highly pipelined”, that’s it…for real Software only tested on one hardware platform – 2.8Ghz Xeon 3Gb ram

Bad analysis of their methodology Hard to follow Unclear how to reproduce Unclear results  Questionable standard datesets 120Mhz??? 10 cycles/CAM stage?????