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    [PATCH] cpuset memory spread slab cache optimizations · c61afb18
    Paul Jackson authored
    The hooks in the slab cache allocator code path for support of NUMA
    mempolicies and cpuset memory spreading are in an important code path.  Many
    systems will use neither feature.
    This patch optimizes those hooks down to a single check of some bits in the
    current tasks task_struct flags.  For non NUMA systems, this hook and related
    code is already ifdef'd out.
    The optimization is done by using another task flag, set if the task is using
    a non-default NUMA mempolicy.  Taking this flag bit along with the
    PF_SPREAD_PAGE and PF_SPREAD_SLAB flag bits added earlier in this 'cpuset
    memory spreading' patch set, one can check for the combination of any of these
    special case memory placement mechanisms with a single test of the current
    tasks task_struct flags.
    This patch also tightens up the code, to save a few bytes of kernel text
    space, and moves some of it out of line.  Due to the nested inlines called
    from multiple places, we were ending up with three copies of this code, which
    once we get off the main code path (for local node allocation) seems a bit
    wasteful of instruction memory.
    Signed-off-by: default avatarPaul Jackson <>
    Signed-off-by: default avatarAndrew Morton <>
    Signed-off-by: default avatarLinus Torvalds <>