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    SubjectRe: [RFC] Simplify node/zone portion of page->flags
    Matthew Dobson <colpatch@us.ibm.com> wrote:
    >
    > Currently we keep track of a pages node & zone in the top 8 bits (on
    > 32-bit arches, 10 bits on 64-bit arches) of page->flags. We typically
    > do: node_num * MAX_NR_ZONES + zone_num = 'nodezone'. It's non-trivial
    > to break this 'nodezone' back into node and zone numbers. This patch
    > modifies the way we compute the index to be: (node_num << ZONE_SHIFT) |
    > zone_num. This makes it trivial to recover either the node or zone
    > number with a simple bitshift. There are many places in the kernel
    > where we do things like: page_zone(page)->zone_pgdat->node_id to
    > determine the node a page belongs to. With this patch we save several
    > pointer dereferences, and it boils down to shifting some bits.

    This rather conflicts with the patch from Jesse which I have. Can you guys
    work that out and let me know when you're done?

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