Its the Software, Stupid

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Its the Software, Stupid

• James Larus
• Microsoft Research
• April 2005

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Transactional Memory

• Promising abstraction for concurrent programming
• CMPs bring problems to the forefront
• Mechanism lives in software environment
• simple hardware transactions may not provide
  appropriate semantics

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Example 1 Conflicting Abstractions
Code
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Example 1 Conflicting Abstractions
Code
Transactional Memory
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Example 1 Conflicting Abstractions
Code
GC
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Example 1 Conflicting Abstractions
Code
GC
TM
TM
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Example 2 Nested Transactions
Code
Libraries
Components
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Example 2 Nested Transactions
Code
Code
Libraries
Components
Libraries
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Example 3 IO
Code
TM
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Summary

• Not starting with a clean slate
• TM must work within existing environment
• changes to use TM will be large
• unrealistic to change everything at once