Messages in this thread | | | From | "Eric W. Biederman" <> | Date | Tue, 15 Sep 2015 09:01:52 -0500 | Subject | Re: Optimising USERNS mapping translation. |
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On September 15, 2015 7:35:45 AM CDT, Aleksa Sarai <cyphar@cyphar.com> wrote: >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?
Is this a homework question? It sounds like one.
If you need more than about two extents you are managing your uids very badly.
As for the nested namespaces and 5 extents limit. I will let you read the code and think about that one.
Eric
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