fs: re-order super_block to remove 16 bytes of padding on 64bit builds (270ba5f7) · Commits · 戴 / test

re-order structure super_block to remove 16 bytes of alignment padding on 64bit builds. This shrinks the size of super_block from 712 to 696 bytes so requiring one fewer 64 byte cache lines. Signed-off-by:

Richard Kennedy <richard@rsk.demon.co.uk> ----- patch against 2.6.33-rc5 compiled & tested on x86_64 AMDX2 desktop machine. I've been running with this patch applied for several weeks with no problems. regards Richard Signed-off-by:

Al Viro <viro@zeniv.linux.org.uk>

include/linux/fs.h

+6 −6

Original line number	Diff line number	Diff line
		@@ -1314,9 +1314,9 @@ extern spinlock_t sb_lock;
		struct super_block {
		struct list_head s_list; /* Keep this first */
		dev_t s_dev; /* search index; _not_ kdev_t */
		unsigned long s_blocksize;
		unsigned char s_blocksize_bits;
		unsigned char s_dirt;
		unsigned char s_blocksize_bits;
		unsigned long s_blocksize;
		loff_t s_maxbytes; /* Max file size */
		struct file_system_type *s_type;
		const struct super_operations *s_op;
		@@ -1357,16 +1357,16 @@ struct super_block {
		void s_fs_info; / Filesystem private info */
		fmode_t s_mode;

		/* Granularity of c/m/atime in ns.
		Cannot be worse than a second */
		u32 s_time_gran;

		/*
		* The next field is for VFS only. No filesystems have any business
		* even looking at it. You had been warned.
		*/
		struct mutex s_vfs_rename_mutex; /* Kludge */

		/* Granularity of c/m/atime in ns.
		Cannot be worse than a second */
		u32 s_time_gran;

		/*
		* Filesystem subtype. If non-empty the filesystem type field
		* in /proc/mounts will be "type.subtype"

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