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    Subjectfs/eventpoll : reduce sizeof(struct epitem)
    Hi Davide

    On a x86_64 platform, I noticed that the size of (struct epitem) is 136
    bytes, rounded to 192 (because of L1_CACHE alignment of 64 bytes)

    If you reorder some fields of this structure, we can reduce the size to
    128 bytes.

    The rationale is to group nwait & fd integer (32bits) fields, instead of
    mixing them with pointers (64 bits)

    See you

    Eric Dumazet

    diff -u linux-2.6.2/fs/eventpoll.c.save linux-2.6.2/fs/eventpoll.c
    --- eventpoll.c.save 2004-02-04 14:59:49.000000000 +0100
    +++ eventpoll.c 2004-02-04 15:02:20.000000000 +0100
    @@ -241,14 +241,15 @@
    /* Number of active wait queue attached to poll operations */
    int nwait;

    + /* The file descriptor this item refers to */
    + int fd;
    +
    /* List containing poll wait queues */
    struct list_head pwqlist;

    /* The "container" of this item */
    struct eventpoll *ep;

    - /* The file descriptor this item refers to */
    - int fd;

    /* The file this item refers to */
    struct file *file;
    -
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