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    Subject[PATCH] mm/slab.c : prefetchw the start of new allocated objects
    [MM] slab.c : prefetchw the start of new allocated objects

    Most of objects returned by __cache_alloc() will be written by the caller,
    (but not all callers want to write all the object, but just at the begining)
    prefetchw() tells the modern CPU to think about the future writes, ie start
    some memory transactions in advance.

    Some CPU lacks a prefetchw() and currently do nothing, so I ask this question :
    Should'nt make prefetchw() do at least a prefetch() ? A read hint is better than nothing.

    Signed-off-by: Eric Dumazet <>

    diff -Nru linux-2.6.13-rc4/mm/slab.c linux-2.6.13-rc4-ed/mm/slab.c
    --- linux-2.6.13-rc4/mm/slab.c 2005-07-29 00:44:44.000000000 +0200
    +++ linux-2.6.13-rc4-ed/mm/slab.c 2005-07-29 10:48:45.000000000 +0200
    @@ -2166,6 +2166,7 @@
    objp = cache_alloc_debugcheck_after(cachep, flags, objp, __builtin_return_address(0));
    + prefetchw(objp);
    return objp;
     \ /
      Last update: 2005-07-29 11:10    [W:0.020 / U:0.160 seconds]
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