Messages in this thread | | | Subject | Re: [PATCH v10 3/3] mm: add anonymous vma name refcounting | From | David Hildenbrand <> | Date | Wed, 6 Oct 2021 11:27:45 +0200 |
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On 06.10.21 10:27, Michal Hocko wrote: > On Tue 05-10-21 23:57:36, John Hubbard wrote: > [...] >> 1) Yes, just leave the strings in the kernel, that's simple and >> it works, and the alternatives don't really help your case nearly >> enough. > > I do not have a strong opinion. Strings are easier to use but they > are more involved and the necessity of kref approach just underlines > that. There are going to be new allocations and that always can lead > to surprising side effects. These are small (80B at maximum) so the > overall footpring shouldn't all that large by default but it can grow > quite large with a very high max_map_count. There are workloads which > really require the default to be set high (e.g. heavy mremap users). So > if anything all those should be __GFP_ACCOUNT and memcg accounted. > > I do agree that numbers are just much more simpler from accounting, > performance and implementation POV.
+1
I can understand that having a string can be quite beneficial e.g., when dumping mmaps. If only user space knows the id <-> string mapping, that can be quite tricky.
However, I also do wonder if there would be a way to standardize/reserve ids, such that a given id always corresponds to a specific user. If we use an uint64_t for an id, there would be plenty room to reserve ids ...
I'd really prefer if we can avoid using strings and instead using ids.
-- Thanks,
David / dhildenb
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