fs/eventpoll : reduce sizeof(struct epitem)

[dada1 <dada1@cosmosbay.com>]

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;