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    SubjectRe: [PATCH -v3 6/8] fsnotify: add group priorities
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    On Mon, 2008-12-01 at 10:20 -0500, Eric Paris wrote:
    >
    > > I can
    > > imagine for many groups and limit range a priority list might be better
    > > suited.
    >
    > talking about plist.h? Since I don't allow 2 groups with the same
    > priority I'd say a lot of the plist code would just be overhead (the
    > prio list and the node list would be the same)
    >
    > That's not a big deal since I don't really care about the add/remove
    > code paths since they are all notification overhead/setup/teardown. I
    > would think that cleaner simpler code would probably be a better idea
    > rather than performance for these areas especially since it looks like
    > the speed critical parts of plists (list_for_each_entry) would be the
    > exact same.
    >
    > what I don't see is plists being protected by RCU and looking at
    > plist_del it doesn't seem like it would be rcu safe. RCU safe plists
    > might be a good idea, but for now I think I should just do my own
    > priority listing so I don't have to hold a lock while I walk the group
    > list (that path is VERY hot)

    plist.h provides a 2d structure, where you can iterate the priorities in
    constant time no matter how many items of any one priority are enqueued.

    Its basically a list of lists.

    If as you say, you only have a hand full of items, there is no point.




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