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    SubjectRe: [PATCH v2 3/9] mm, page_owner: convert page_owner_inited to static key
    On Wed 25-11-15 16:25:33, Peter Zijlstra wrote:
    > On Wed, Nov 25, 2015 at 04:08:11PM +0100, Vlastimil Babka wrote:
    > > Now I admit I have no idea if there are architectures that don't support jump
    > > labels *and* have an expensive atomic read, and whether we care?
    >
    > atomic_read() is basically always READ_ONCE(), there's a few archs that
    > implement it in asm with a 'weird' load instruction, but its still a
    > load. The worst is I think an uncached load for blackfin or somesuch.
    >
    > There's plenty archs that do not support the jump label bits, but
    > typically you don't care much about those. I'm not aware of an arch that
    > cannot fundamentally implement jump_label support if they wanted to.

    OK, I see. Thanks for the clarification! Then I do not have any
    objections.

    --
    Michal Hocko
    SUSE Labs


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