Commit e08b061e authored Aug 07, 2009 by Eric Paris Committed by Al Viro Sep 24, 2009

Audit: reorganize struct audit_watch to save 8 bytes



pahole showed that struct audit_watch had two holes:

struct audit_watch {
        atomic_t                   count;                /*     0     4 */

        /* XXX 4 bytes hole, try to pack */

        char *                     path;                 /*     8     8 */
        dev_t                      dev;                  /*    16     4 */

        /* XXX 4 bytes hole, try to pack */

        long unsigned int          ino;                  /*    24     8 */
        struct audit_parent *      parent;               /*    32     8 */
        struct list_head           wlist;                /*    40    16 */
        struct list_head           rules;                /*    56    16 */
        /* --- cacheline 1 boundary (64 bytes) was 8 bytes ago --- */

        /* size: 72, cachelines: 2, members: 7 */
        /* sum members: 64, holes: 2, sum holes: 8 */
        /* last cacheline: 8 bytes */
};      /* definitions: 1 */

by moving dev after count we save 8 bytes,  actually improving cacheline
usage.  There are typically very few of these in the kernel so it won't be
a large savings, but it's a good thing no matter what.

Signed-off-by: Eric Paris <eparis@redhat.com>
Signed-off-by: Al Viro <viro@zeniv.linux.org.uk>

parent 94a8d5ca

kernel/audit_watch.c

+1 −1

Original line number	Original line	Diff line number	Diff line
	@@ -45,8 +45,8 @@

	struct audit_watch {		struct audit_watch {
	atomic_t count; /* reference count */		atomic_t count; /* reference count */
	char path; / insertion path */
	dev_t dev; /* associated superblock device */		dev_t dev; /* associated superblock device */
			char path; / insertion path */
	unsigned long ino; /* associated inode number */		unsigned long ino; /* associated inode number */
	struct audit_parent parent; / associated parent */		struct audit_parent parent; / associated parent */
	struct list_head wlist; /* entry in parent->watches list */		struct list_head wlist; /* entry in parent->watches list */

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