Feature #6199: Organize gc.c a bit

• Status: Closed
• Assignee: authorNari (Narihiro Nakamura)
• Target version: 2.0.0

[funny_falcon (Yura Sokolov)]

1. Move immutable fields from struct heaps_slot and struct sorted_heaps_slot into struct heaps_header.
   One exception is limit field, but it starts to be mutable just before freeing a heaps_header, so that it is not big issue.
2. Embed bitmap into struct heaps_slot
3. Change free_unused_heaps to free_unused_heap, so that it will not be called on every GC round, but only when page should be freed.
   While free_unused_heaps does not consume much time (it is invisible in profiler), but regular application has no need in calling this function every time.

https://github.com/ruby/ruby/pull/108
https://github.com/ruby/ruby/pull/108.patch

[mame (Yusuke Endoh)]

• Status changed from Open to Assigned

[authorNari (Narihiro Nakamura)]

Hi,

I'm sorry for late reply. I've just reviewed these.
I'm not sure that 3. improves a performance, because it's using binary search each one slot.

I don't like 2.

I will accept 1.

Thank you!

[funny_falcon (Yura Sokolov)]

I'm not sure that 3. improves a performance, because it's using binary search each one slot.

Well, free_unused_heaps runs on each GC and does linear scan, and free_unused_heap runs only on heap's freeing.
Heap freeing occurs rare in typical long running application, so that it is possibly that linear scan for each GC is overkill.

But I could not prove it :)

[authorNari (Narihiro Nakamura)]

• Status changed from Assigned to Closed
• % Done changed from 0 to 100

This issue was solved with changeset r37613.
Yura, thank you for reporting this issue.
Your contribution to Ruby is greatly appreciated.
May Ruby be with you.

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• gc.c: move immutable fields from struct heaps_slot and struct
  sorted_heaps_slot into struct heaps_header.
  Based on a patch from Sokolov Yura [Feature #6199][ruby-core:43592]