Hash Sorting for Triplet Matching

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Hash Sorting for Triplet Matching

• Jinyuan Wu, M. Wang
• For BTeV collaboration
• Dec. 2002

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Hash Sorter
7
6
5
4
3
2
1
0
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Hash Sorting and Then?
DATA
DATA
Hash Sorter
Hash Sorter
DSP
DSP
Hardware Triplet Matcher
Buffer Manager
Buffer Manager

• Directly send to C algorithm.
• Send to hardware algorithm and then C algorithm.

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However

• Hash sorting alone can not do the whole triplet
  matching job.

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Hash Sorting and Feed to C Code

• Data are just sorted, no cutting.
• Sorted data let C code finds possible match in
  small number of combinations.

DATA
Hash Sorter
DSP
Buffer Manager
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Hash Sorting and Feed to Hardware Triplet Matcher

• Data are just sorted, no cutting.
• Sorted data reduce the functional block array
  size, so that it will fit in FPGA.

DATA
Hash Sorter
DSP
Hardware Triplet Matcher
Buffer Manager
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Hash Sorting (For Triplet Matching)
Triplets sorted by (dx/dz)
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Hash Sorter (How)
Int. Triplets
Ext. Triplets
dx
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Hash Sorter (Implementation)
DOUT
DIN
A_write
DATA RAM
B
B(DIN)
(B,C)
Count for DOUT
(C1)
C

• Large number of bins.
• 2 CLK/write.
• 1 CLK/read.
• Ping-pong structure.

COUNT RAM
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Results

• See the hashT2Tr.pdf file

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Summary

• Int. and Ext. triplets are sorted in 800um bins.
• lt 0.5 matching triplets are beyond 2 neighboring
  bins.
• Feeding to C code
• Factor of 12 combination reduction. (both 132ns
  and 396ns cases)
• Feeding to Hardware Triplet Matcher
• Max. query list size 16 for 132ns case. (gt80
  without hash binning)
• Max. query list size 32 for 396ns case. (gt200
  without hash binning)

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End