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    SubjectRe: [PATCH] Cpuset: rcu optimization of page alloc hook
    On Tue, 13 Dec 2005, Eric Dumazet wrote:

    > Say you move to read mostly most of struct kmem_cache *, they are guaranteed
    > to stay in 'mostly read'.

    True but then this variable is not frequently read. So false sharing would
    not have much of an impact.

    > Mixing for example filp_cachep and dcache_lock in the same cache line is not a
    > good thing. And this is what happening on typical kernel :
    > c04f15f0 B dcache_lock
    > c04f15f4 B names_cachep
    > c04f15f8 B filp_cachep
    > c04f15fc b rename_lock
    > I do think we should have defined a special section for very hot (and written)
    > spots. It's more easy to locate thos hot spots than 'mostly read and shared by
    > all cpus without cache ping pongs' places...

    In that case I would think we would want to place these very hot
    spots in their own cacheline and control which variables end up in
    that particular cacheline. Define a struct something {} and put all
    elements that need to go into the same cacheline into that struct.
    Then cacheline align the struct.
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      Last update: 2005-12-13 18:45    [W:0.020 / U:3.488 seconds]
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