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GC tuning_factor might need more tuning #53485

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@d-netto

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I think there might be some work left on getting a suitable value for the tuning_factor in src/gc.c .

I bumped it from 2e4 to 2e5 and got more than a 2x reduction in GC times with maximum heap size decreasing as well. This is for append.jl FWIW.

  • 2e4:
┌─────────┬────────────┬─────────┬───────────┬────────────┬──────────────┬───────────────────┬──────────┬────────────┐
│         │ total time │ gc time │ mark time │ sweep time │ max GC pause │ time to safepoint │ max heap │ percent gc │
│         │         ms │      ms │        ms │         ms │           ms │                us │       MB │          % │
├─────────┼────────────┼─────────┼───────────┼────────────┼──────────────┼───────────────────┼──────────┼────────────┤
│ minimum │        952 │     280 │       177 │        103 │           50 │                95 │     3698 │         29 │
│  median │        959 │     286 │       177 │        107 │           50 │               101 │     3700 │         30 │
│ maximum │        964 │     286 │       179 │        108 │           56 │               103 │     4032 │         30 │
│   stdev │          6 │       3 │         1 │          3 │            4 │                 4 │      192 │          0 │
└─────────┴────────────┴─────────┴───────────┴────────────┴──────────────┴───────────────────┴──────────┴────────────┘
  • 2e5:
┌─────────┬────────────┬─────────┬───────────┬────────────┬──────────────┬───────────────────┬──────────┬────────────┐
│         │ total time │ gc time │ mark time │ sweep time │ max GC pause │ time to safepoint │ max heap │ percent gc │
│         │         ms │      ms │        ms │         ms │           ms │                us │       MB │          % │
├─────────┼────────────┼─────────┼───────────┼────────────┼──────────────┼───────────────────┼──────────┼────────────┤
│ minimum │        790 │     116 │        39 │         77 │           40 │                54 │     3246 │         15 │
│  median │        799 │     120 │        39 │         81 │           41 │                63 │     3249 │         15 │
│ maximum │        802 │     126 │        40 │         86 │           50 │                67 │     3249 │         16 │
│   stdev │          6 │       5 │         1 │          4 │            5 │                 7 │        2 │          1 │
└─────────┴────────────┴─────────┴───────────┴────────────┴──────────────┴───────────────────┴──────────┴────────────┘

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