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Groups > linux.kernel > #1225039

Optimising USERNS mapping translation.

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Hi,

I'm wondering if there's a reason that we do a linear search for the
mapping translations between kuid_t and uid_t. Surely something like a
radix trie would (potentially) allow for better storage and lookup? Is
the whole "an extent fits in a cache line" a good enough optimisation
that it would be pointless to use a better structure? Also, is there a
good reason why we have UID_GID_MAP_MAX_EXTENTS = 5 (other than the
one cache line thing)? Surely it's not more efficient to have to
create a bunch of nested namespaces in order to have more than 5
extents?

-- 
Aleksa Sarai (cyphar)
www.cyphar.com
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Optimising USERNS mapping translation. Aleksa Sarai <cyphar@cyphar.com> - 2015-09-15 14:40 +0200
  Re: Optimising USERNS mapping translation. "Eric W. Biederman" <ebiederm@xmission.com> - 2015-09-15 16:10 +0200

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