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    SubjectRe: [PATCH 2/6] change alloc function in pcpu_alloc_pages
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    On Fri, 2010-04-16 at 11:07 -0500, Christoph Lameter wrote:
    > On Thu, 15 Apr 2010, Minchan Kim wrote:
    >
    > > I don't want to remove alloc_pages for UMA system.
    >
    > alloc_pages is the same as alloc_pages_any_node so why have it?
    >
    > > #define alloc_pages alloc_page_sexact_node
    > >
    > > What I want to remove is just alloc_pages_node. :)
    >
    > Why remove it? If you want to get rid of -1 handling then check all the
    > callsites and make sure that they are not using -1.
    >
    > Also could you define a constant for -1? -1 may have various meanings. One
    > is the local node and the other is any node.

    NUMA_NO_NODE is #defined as (-1) and can be used for this purpose. '-1'
    has been replaced by this in many cases. It can be interpreted as "No
    node specified" == "any node is acceptable". But, it also has multiple
    meanings. E.g., in the hugetlb sysfs attribute and sysctl functions it
    indicates the global hstates [all nodes] vs a per node hstate. So, I
    suppose one could define a NUMA_ANY_NODE, to make the intention clear at
    the call site.

    I believe that all usage of -1 to mean the local node has been removed,
    unless I missed one. Local allocation is now indicated by a mempolicy
    mode flag--MPOL_F_LOCAL. It's treated as a special case of
    MPOL_PREFERRED.

    > The difference is if memory
    > policies are obeyed or not. Note that alloc_pages follows memory policies
    > whereas alloc_pages_node does not.
    >
    > Therefore
    >
    > alloc_pages() != alloc_pages_node( , -1)
    >
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