[Libguestfs] [PATCH libguestfs 1/2] ocaml/implicit_close test: collect all currently unreachable blocks

[Laszlo Ersek]

On 6/1/23 13:18, Richard W.M. Jones wrote:
> [Sorry, not read the other replies yet, in meetings all day today]
> 
> On Wed, May 31, 2023 at 05:13:58PM +0100, Richard W.M. Jones wrote:
>> To start with I have opened a discussion topic.  We can think about
>> opening bugs later.
>>
>> https://discuss.ocaml.org/t/ocaml-heap-fsck-and-forcing-collection-of-unreachable-objects/12281
> 
> There were some replies to this thread.  One open merge request is
> notable - it adds compaction back:
> 
>   https://github.com/ocaml/ocaml/pull/12193
> 
> although only for "small" blocks, less than 128 * 8-byte words, which
> probably covers everything we do.

We likely don't have a structure type larger than 1KB :)

> It seems like full_major is the way to force freeing of unreachable
> objects, in all versions of OCaml.

Ah, does that mean we don't need a version check here, after all? IIRC,
you said that in OCaml 4, "compact" was a superset of "full_major". If
"full_major" is sufficient for finalizing unreachable objects on OCaml 4
too, then we can downgrade "compact" to "full_major" regardless of OCaml
version.

Laszlo