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Introduction Storage Models Analysis and Evaluation Summary
Weaving Relations for Cache Performance
Johannes Kern
Universit¨ at T¨ ubingen
Introduction Storage Models Analysis and Evaluation Summary
Motivation I
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Weaving Relations for Cache Performance Johannes Kern Universit at - - PowerPoint PPT Presentation
Weaving Relations for Cache Performance Johannes Kern Universit at - - PowerPoint PPT Presentation
Introduction Storage Models Analysis and Evaluation Summary Weaving Relations for Cache Performance Johannes Kern Universit at T ubingen 03.12.2010 Introduction Storage Models Analysis and Evaluation Summary Motivation I 2
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Introduction Storage Models Analysis and Evaluation Summary
Motivation II
Key memory bottleneck: Data cache misses 50-90% of total memory-related stall time
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Introduction Storage Models Analysis and Evaluation Summary
Remedy
Create cache-conscious storage model Maximize spatial locality Maintain good I/O performance
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Introduction Storage Models Analysis and Evaluation Summary
Remedy
Create cache-conscious storage model Maximize spatial locality Maintain good I/O performance
→ Partition Attributes Across (PAX)
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Introduction Storage Models Analysis and Evaluation Summary
Cache Evaluation
Relation R SSN name age 0962 Jane 30 7658 John 45 3589 Jim 20 5523 Susan 52 Query
SELECT name FROM R WHERE age < 40;
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Introduction Storage Models Analysis and Evaluation Summary
N-ary Storage Model (NSM)
Inter-record spatial locality ✪ Low record reconstruction cost ✦
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Introduction Storage Models Analysis and Evaluation Summary
Decomposition Storage Model (DSM)
Inter-record spatial locality ✦ Low record reconstruction cost ✪
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Introduction Storage Models Analysis and Evaluation Summary
Partition Attributes Across (PAX)
Inter-record spatial locality ✦ Low record reconstruction cost ✦
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Introduction Storage Models Analysis and Evaluation Summary
Evaluation Characteristic NSM DSM PAX Inter-record spatial locality ✪ ✦ ✦ Low record reconstruction cost ✦ ✪ ✦
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Introduction Storage Models Analysis and Evaluation Summary
Setup
Dell 6400 PII Xeon/MT Windows NT 4.0 Pentium II Xeon 400Mhz
16 kB split L1 cache 512 kB unified L2 cache 32 Byte cache blocks
512 MB main memory 100 Mhz system bus
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Introduction Storage Models Analysis and Evaluation Summary
Workload
Query
SELECT AVG( a ) FROM R WHERE b > Lo AND b < Hi
Eight 8 Byte attributes 1.2 million records
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Introduction Storage Models Analysis and Evaluation Summary
Record Reconstruction Costs
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Introduction Storage Models Analysis and Evaluation Summary
Memory Stall Time Analysis
Cache misses
NSM: 1 per record PAX: 1 every n records (n = cacheblocksize
attributesize )
PAX saves 75% L2 data cache misses compared to NSM
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Introduction Storage Models Analysis and Evaluation Summary
Summary
Data access to cache hierarchy major performance bottleneck NSM incurs negative effects on data cache performance DSM incurs high record reconstruction costs PAX combines the good attributes of NSM/DSM PAX summary PAX groups values for the same attribute together in minipages, combining inter-record spatial locality and high data cache performance with minimal record reconstruction cost at no extra storage overhead.
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