From: "mame (Yusuke Endoh)" <noreply@...>
Date: 2021-12-09T12:02:30+00:00
Subject: [ruby-core:106592] [Ruby master Feature#18364] Add GC.stat_pool for Variable Width Allocation

Issue #18364 has been updated by mame (Yusuke Endoh).


This ticket was discussed at today's dev-meeting. Matz had directly asked @tenderlovemaking for a few things. I record them as far as I remember:

* Instead of adding a new method, it looks good for `GC.stat` to return a nested data structure format like #4.
* The terminology "pool" looks not very good. How about "size_heap"?

----------------------------------------
Feature #18364: Add GC.stat_pool for Variable Width Allocation
https://bugs.ruby-lang.org/issues/18364#change-95257

* Author: peterzhu2118 (Peter Zhu)
* Status: Open
* Priority: Normal
* Assignee: matz (Yukihiro Matsumoto)
----------------------------------------
# GitHub PR: https://github.com/ruby/ruby/pull/5177

We're proposing an API to get statistics for size pools for Variable Width Allocation similar to `GC.stat`. This will make it easier for us (and other developers) to tune VWA.

Before 3.1 release, we plan to keep this method hidden from the documentation using `:nodoc:` since it is not useful when not using VWA.

For example:

```ruby
# Get stats for size pool 2
puts GC.stat_pool(2)
#=> {:slot_size=>160, :heap_allocatable_pages=>80, :heap_eden_pages=>14, :heap_eden_slots=>1424, :heap_tomb_pages=>0, :heap_tomb_slots=>0}
puts GC.stat_pool(2, :heap_eden_pages)
#=> 14
```

We aim to keep the keys in the outputted hash the same as the keys used in `GC.stat`.

We chose to implement a new method instead of re-using an existing API (`GC.stat`) because the keys returned by `GC.stat_pool` will not be the same as `GC.stat`. We believe that having `GC.stat` return different shapes of hashes based on its arguments is confusing.




-- 
https://bugs.ruby-lang.org/

Unsubscribe: <mailto:ruby-core-request@ruby-lang.org?subject=unsubscribe>
<http://lists.ruby-lang.org/cgi-bin/mailman/options/ruby-core>