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 No Collector stack
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 Lacking 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),
Baker, Henry G. List Processing in Real Time on a Serial Computer. Comm ACM 21, 4 (Apr 1978)