Commit 83b7b44e authored Dec 06, 2006 by Eric Dumazet Committed by Linus Torvalds Dec 07, 2006

[PATCH] fs: reorder some 'struct inode' fields to speedup i_size manipulations



On 32bits SMP platforms, 64bits i_size is protected by a seqcount
(i_size_seqcount).

When i_size is read or written, i_size_seqcount is read/written as well, so
it make sense to group these two fields together in the same cache line.

This patch moves i_size_seqcount next to i_size, and also moves i_version
to let offsetof(struct inode, i_size) being 0x40 instead of 0x3c (for
32bits platforms).

For 64 bits platforms, i_size_seqcount doesnt exist, and the move of a
'long i_version' should not introduce a new hole because of padding.

Signed-off-by: Eric Dumazet <dada1@cosmosbay.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>

parent ea82c740

include/linux/fs.h

+4 −4

Original line number	Diff line number	Diff line
		@@ -548,12 +548,15 @@ struct inode {
		uid_t i_uid;
		gid_t i_gid;
		dev_t i_rdev;
		unsigned long i_version;
		loff_t i_size;
		#ifdef __NEED_I_SIZE_ORDERED
		seqcount_t i_size_seqcount;
		#endif
		struct timespec i_atime;
		struct timespec i_mtime;
		struct timespec i_ctime;
		unsigned int i_blkbits;
		unsigned long i_version;
		blkcnt_t i_blocks;
		unsigned short i_bytes;
		spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */
		@@ -598,9 +601,6 @@ struct inode {
		void *i_security;
		#endif
		void i_private; / fs or device private pointer */
		#ifdef __NEED_I_SIZE_ORDERED
		seqcount_t i_size_seqcount;
		#endif
		};

		/*

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