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    SubjectRe: Lockless page cache test results
    Andrew Morton wrote:
    > Jens Axboe <axboe@suse.de> wrote:
    >
    >>Are there cases where the lockless page cache performs worse than the
    >>current one?
    >
    >
    > Yeah - when human beings try to understand and maintain it.

    Have any tried yet? ;)

    I won't deny it is complex (because I don't like when I make the
    same point and people go on to take great trouble to convince me
    how simple it is!).

    But I hope it isn't _too_ bad. It is basically a dozen line
    function at the core, and that gets used to implement
    find_get_page, find_lock_page. Their semantics remain the same,
    so that's where the line is drawn (plus minor things, like an
    addition for reclaim's remove-from-pagecache protocol).

    IMO the rcu radix tree is probably the most complex bit... but
    that pales in comparison to things like our prio tree, or RCU
    trie.

    >
    > The usual tradeoffs apply ;)

    Definitely. It isn't fun if you just take the patch and merge it.

    --
    SUSE Labs, Novell Inc.
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