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VW Object Memory Management
- 1. VisualWorks Object Memory Management Andrés Valloud
- 2. Structure
- 3. Eden
- 4. SA Eden SB
- 5. SA Eden SB Old
- 6. SA Eden SB Old Perm
- 7. Evolution
- 9. Scavenge 1
- 10. Scavenge 2
- 11. Scavenge 3
- 12. Scavenge 4
- 13. Tenured
- 14. IGC / GC
- 15. Perm save
- 16. Global GC R IP
- 17. But, speaking of GC...
- 18. SA Eden SB Old Perm
- 19. Scavenge finds SA live objects Eden SB faster RT Old Perm
- 20. Scavenge finds SA live objects Eden SB faster RT Old IGC / GC find Old live objects Perm RT faster
- 21. Responsibilities
- 22. SA Eden SB RT Old Old Perm RT
- 23. VM scavenges SA Eden new space SB RT Old Old Perm RT
- 24. VM scavenges SA VI must ensure Eden new space SB success RT Old Old Perm RT
- 25. VM scavenges SA VI must ensure Eden new space SB success VM signals low memory RT Old semaphore Old Perm RT
- 26. VM scavenges SA VI must ensure Eden new space SB success VM signals low VI manages old memory RT Old space (GC, semaphore grow, shrink) Old Perm RT
- 27. VM scavenges SA VI must ensure Eden new space SB success VM signals low VI manages old memory RT Old space (GC, semaphore grow, shrink) VM (few) Old VI memory Perm policy classes fixed actions RT
- 28. Memory policies
- 29. Worst case SA Eden scavenge SB RT Old Old Perm RT
- 30. Worst case SA Eden and Eden scavenge SB SA or SB full RT Old Old Perm RT
- 31. Worst case SA Eden and Eden scavenge SB SA or SB full RT Old RT grows Old Perm RT
- 32. Worst case SA Eden and Eden scavenge SB SA or SB full RT Old RT grows Old Perm Old RT grows RT
- 33. Worst case SA Eden and scavenge Eden SB SA or SB full due to GC Stack RT Old RT grows Stack zone full, flushed to object memory Old Perm Old RT grows RT
- 34. The picture Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 35. The picture Growth Worst Case Increments Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 36. Improvements since VisualWorks 7.7
- 37. Fixed since VW 7.7 ObjectMemory>>igcState ... aborting ifTrue: [^#aborting]. ... MemoryPolicy>>dealWithIGC ... memoryStatus igcState = #aborted ifTrue: [“recover from IGC abort”]. ...
- 38. Fixed since VW 7.7 ObjectMemory>>igcState ... aborting ifTrue: [^#aborting]. ... IGC does not recover from stack overflow MemoryPolicy>>dealWithIGC ... memoryStatus igcState = #aborted ifTrue: [“recover from IGC abort”]. ...
- 39. Fixed since VW 7.7 Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 40. Fixed since VW 7.7 IGC as last resort, bogus emergencies Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 41. Fixed since VW 7.7 VM crash due to scavenge failure Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 42. Fixed since VW 7.7 Too low for modern applications Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 43. Fixed since VW 7.7 Growth Worst Case Increments Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 44. Fixed since VW 7.7 Tiny growth increment, excessive GC Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 45. Fixed since VW 7.7 Tiny growth increment, fragmentation Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 46. Fixed since VW 7.7 Low free memory limit, even more GC Worst Case Scavenge Upper 0 Memory Bound Growth Image Emergency Regime Size Threshold Bound
- 47. New technology
- 48. E S T S New technology T
- 49. E S T S New technology T •MemoryPolicyChecker
- 50. E S T S New technology T •MemoryPolicyChecker •MemoryPolicyTuner
- 51. E S T S New technology T •MemoryPolicyChecker •MemoryPolicyTuner •MemoryPolicyStressTest
- 53. Before and after
- 54. Before Upper 0 Memory Bound Upper 0 Memory Bound After
- 55. Run time per stress test case, in seconds 40,000 30,000 20,000 10,000 0 A (x100) B (x100) C (x400) D (x40) E (x40) F (x6) G (x6) VW 7.7 legacy MemoryPolicy (with fixes) ~1 day, if they work VW 7.7.1 without sizesAtStartup tuning ~160 minutes VW 7.7.1 default ~73 minutes A: pointer garbage Segmented container Large container B: byte garbage D: byte allocation F: byte allocation C: point creation E: pointer allocation G: pointer allocation
- 56. Print 2 web, ESUG 2009
- 57. Print 2 web, ESUG 2009 X 2.5x faster (with small changes only)
- 58. VisualWorks 7.8 and beyond
- 59. VisualWorks 7.8+ •Fixed space allocation fixed •Improved weak / ephemeron support •IGC performance improvements •GC / IGC mark stack overflow prevention •GC moves large objects back into large space •New -m[1..7] VM switches
- 60. VisualWorks 7.8+ •Fixed space allocation fixed N E •Improved weak / ephemeron support O D •IGC performance improvements •GC / IGC mark stack overflow prevention •GC moves large objects back into large space •New -m[1..7] VM switches
- 61. VisualWorks 7.9
- 62. VisualWorks 7.9 •Up to 40% faster GC
- 63. VisualWorks 7.9 •Up to 40% faster GC •Improved IGC uses less memory
- 64. VisualWorks 7.9 •Up to 40% faster GC •Improved IGC uses less memory •Adaptive time based memory policy IGC driver
- 65. VisualWorks 7.9 •Up to 40% faster GC •Improved IGC uses less memory •Adaptive time based memory policy IGC driver •Memory policy IGC smart abort
- 66. VisualWorks 7.9 •Up to 40% faster GC •Improved IGC uses less memory •Adaptive time based memory policy IGC driver •Memory policy IGC smart abort •Memory policy IGC switch
- 67. VisualWorks 7.9 •Up to 40% faster GC •Improved IGC uses less memory •Adaptive time based memory policy IGC driver •Memory policy IGC smart abort •Memory policy IGC switch •Updates to the OldRT, become:, fixed space...
- 68. VisualWorks 7.9 •Up to 40% faster GC O N E •Improved IGC uses less memory D •Adaptive time based memory policy IGC driver •Memory policy IGC smart abort •Memory policy IGC switch •Updates to the OldRT, become:, fixed space...
- 69. Questions?