An Efficient Profile-Analysis Framework for Data-Layout Optimizations

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An Efficient Profile-Analysis Framework for
Data-Layout Optimizations

• By
• Shai Rubin,
• Rastislav Bodik,
• Trishul Chilimbi

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Data-Layout Optimization

• To improve memory hierarchy performance by
  exploiting spatial locality
• Group the data that is accessed together
• Minimizing cache conflicts
• Optimizations
• Field rearrangement in an object
• Object rearrangement in the heap
• Object inlining

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Motivation

• A solution to find the optimal layout is NP-hard
  and also poorly approximable
• All these techniques are actually heuristics and
  no guarantee of effectiveness and robustness
• A naïve approach is tedious

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Solution

• A generalized framework to determine the best
  layout for a given program
• Unifying existing profile-based data layout
  optimizations
• A very efficient way of evaluating a candidate
  layout with simulation

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Optimization Evaluation

• Memoization
• Dynamic programming
• Whole Program Misses
• The representation omits references that can
  never suffer any memory fault
• Ex. abba
• On demand Cache simulation

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Results
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Discussion

• How many applications really use this kind of
  optimizations?
• Some of the optimizations are already automated
  (ex. Object inlining)