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Real-Time List Processing on Serial Computers: Techniques and Limitations

This outline discusses the techniques for list processing in real-time environments on serial computers, focusing on methods such as the Minsky-Feinchel-Yochelson-Cheney-Arnborg (MFYCA) and Baker's serial real-time approach. It covers methods of garbage collection, scanning, and compaction, while addressing limitations in list processing. The presentation also explores access and mutation operations, memory reclamation, and the performance implications of various algorithms, including a detailed analysis of space/time trade-offs and real-time properties, concluding with potential applications and limitations in contemporary computing.

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Real-Time List Processing on Serial Computers: Techniques and Limitations

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Presentation Transcript

  1. List Processing in Real Time on a Serial Computer Cas Craven CS395T: Kathryn S. McKinley 2011

  2. Outline • List processing languages • Copying Gargage Collection Methods • Minsky-Feinchel-Yochelson-Cheney-Arnborg (MFYCA) • Baker’s Serial Real-Time Method • Scanning and compaction • Limitations

  3. List Processing • List elements have two cells, A and R, holding either data or a pointer • Instantiated with CONS • Accessors: CAR, CDR • Mutators: REPLCA REPLCR • Memory reclaimed by garbage collection

  4. MFYCA: Initial (Post Flip)

  5. MFYCA: Copy Registers

  6. MFYCA: Copying

  7. MFYCA: Done

  8. MYCFA: Simple GC • Single pass instead of • Mark • Sweep • Relocate • No Collector stack • Program sees addresses in To Space

  9. Baker’s Algorithm • At each CONS, perform k iterations of the GC loop from MFYCA • Both semispaces now contain accessible cells • Pretend GC completed at time of last flip • Copy all registers immediately after flip • Modify CAR, CDR: Follow forwarding addresses, move cells found in from space and update pointers • New cells placed at top of To Space

  10. Baker’s Algorithm: CONSing (k=2)

  11. Compaction: Breadth First Problem • Locality lost in MYCFA and Baker • Performance: modern memory hierarchy • Space: CDR coding requires linearizing gc • Solution mentioned in Baker: trace whole lists in the cdr direction • Chenney paper: A Nonrecursive List Compacting Algorithm • Details such a method

  12. List Compaction

  13. List Compaction: Circular Lists

  14. Limitations • Designed for a serial processor • Workable on multi-core? Shared memory? • Applicability to other data structures • Stack: separate space or emulate as a list in the heap? • Vectors and Arrays: loss of real-time property • Hash tables: esp. indexed by address?

  15. Conclusion • Contributions • Real-time: bounded time, no GC pause • Doesn’t require parallel GC thread • Space/time tradeoff flexibility with k • Proven correct: no erroneous OOM • Lacking • Primarily concerned with memory space, but bandwidth usage to copy limits performance • Virtual Memory machines suffer increased working set size • Arrays break the real-time property • Empirical Results?

  16. References • 2009 Presentation by Hadi Esmaeilzadeh • Chenney, C.J. A Nonrecursive List Compacting Algorithm. Comm ACM.13, 11 (Nov 1970), 677-678. • Baker, Henry G. List Processing in Real Time on a Serial Computer. Comm ACM 21, 4 (Apr 1978) 280-294.

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