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

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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>
This commit is contained in:
Eric Dumazet 2006-12-06 20:38:53 -08:00 committed by Linus Torvalds
parent ea82c74093
commit 83b7b44e1c
1 changed files with 4 additions and 4 deletions
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8
include/linux/fs.h
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@ -548,12 +548,15 @@ struct inode {
uid_t i_uid; uid_t i_uid;
gid_t i_gid; gid_t i_gid;
dev_t i_rdev; dev_t i_rdev;
unsigned long i_version;
loff_t i_size; loff_t i_size;
#ifdef __NEED_I_SIZE_ORDERED
seqcount_t i_size_seqcount;
#endif
struct timespec i_atime; struct timespec i_atime;
struct timespec i_mtime; struct timespec i_mtime;
struct timespec i_ctime; struct timespec i_ctime;
unsigned int i_blkbits; unsigned int i_blkbits;
unsigned long i_version;
blkcnt_t i_blocks; blkcnt_t i_blocks;
unsigned short i_bytes; unsigned short i_bytes;
spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */
@ -598,9 +601,6 @@ struct inode {
void *i_security; void *i_security;
#endif #endif
void *i_private; /* fs or device private pointer */ void *i_private; /* fs or device private pointer */
#ifdef __NEED_I_SIZE_ORDERED
seqcount_t i_size_seqcount;
#endif
}; };
/* /*