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    SubjectRe: [RFC patch] spindep: add cross cache lines checking
    Date
    On Monday 05 March 2012, Alex Shi wrote:
    > Subject: [PATCH] lockdep: add cross cache lines checking
    >
    > Modern x86 CPU won't hold whole memory bus when executing 'lock'
    > prefixed instructions unless the instruction destination is crossing 2
    > cache lines. If so, it is disaster of system performance.
    >
    > Actually if the lock is not in the 'packed' structure, gcc places it
    > safely under x86 arch. But seems add this checking in
    > CONFIG_DEBUG_LOCK_ALLOC is harmless.

    Have you tried making this a compile-time check using __alignof__?
    I would say that any spinlock in a packed data structure is
    basically a bug, even more so on most other architectures besides
    x86.

    Arnd


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