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| author | Arnaldo Carvalho de Melo <acme@mandriva.com> | 2006-12-06 20:39:53 -0800 |
|---|---|---|
| committer | Linus Torvalds <torvalds@woody.osdl.org> | 2006-12-07 08:39:43 -0800 |
| commit | 12d40e43d251de4fa1f982567fc8b4ee5e858367 (patch) | |
| tree | 91a562fc73af84efe6e8a388ccd2f907c04fa674 /include | |
| parent | 652d3a3ed7610bb09530127ca297b538fe7d245a (diff) | |
| download | linux-12d40e43d251de4fa1f982567fc8b4ee5e858367.tar.bz2 | |
[PATCH] Save some bytes in struct inode
[acme@newtoy net-2.6.20]$ pahole --cacheline 64 fs/inode.o inode
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/linux/dcache.h:86 */
struct inode {
struct hlist_node i_hash; /* 0 8 */
struct list_head i_list; /* 8 8 */
struct list_head i_sb_list; /* 16 8 */
struct list_head i_dentry; /* 24 8 */
long unsigned int i_ino; /* 32 4 */
atomic_t i_count; /* 36 4 */
umode_t i_mode; /* 40 2 */
/* XXX 2 bytes hole, try to pack */
unsigned int i_nlink; /* 44 4 */
uid_t i_uid; /* 48 4 */
gid_t i_gid; /* 52 4 */
dev_t i_rdev; /* 56 4 */
loff_t i_size; /* 60 8 */
struct timespec i_atime; /* 68 8 */
struct timespec i_mtime; /* 76 8 */
struct timespec i_ctime; /* 84 8 */
unsigned int i_blkbits; /* 92 4 */
long unsigned int i_version; /* 96 4 */
blkcnt_t i_blocks; /* 100 4 */
short unsigned int i_bytes; /* 104 2 */
/* XXX 2 bytes hole, try to pack */
spinlock_t i_lock; /* 108 40 */
struct mutex i_mutex; /* 148 76 */
struct rw_semaphore i_alloc_sem; /* 224 64 */
struct inode_operations * i_op; /* 288 4 */
const struct file_operations * i_fop; /* 292 4 */
struct super_block * i_sb; /* 296 4 */
struct file_lock * i_flock; /* 300 4 */
struct address_space * i_mapping; /* 304 4 */
struct address_space i_data; /* 308 188 */
struct list_head i_devices; /* 496 8 */
union ; /* 504 4 */
int i_cindex; /* 508 4 */
__u32 i_generation; /* 512 4 */
/* ---------- cacheline 8 boundary ---------- */
long unsigned int i_dnotify_mask; /* 516 4 */
struct dnotify_struct * i_dnotify; /* 520 4 */
struct list_head inotify_watches; /* 524 8 */
struct mutex inotify_mutex; /* 532 76 */
long unsigned int i_state; /* 608 4 */
long unsigned int dirtied_when; /* 612 4 */
unsigned int i_flags; /* 616 4 */
atomic_t i_writecount; /* 620 4 */
void * i_security; /* 624 4 */
void * i_private; /* 628 4 */
}; /* size: 632, sum members: 628, holes: 2, sum holes: 4 */
[acme@newtoy net-2.6.20]$
So just moving i_mode to after i_bytes we save 4 bytes by nuking both holes:
[acme@newtoy net-2.6.20]$ codiff -V /tmp/inode.o.before fs/inode.o
/pub/scm/linux/kernel/git/acme/net-2.6.20/fs/inode.c:
struct inode | -4
i_mode;
from: umode_t /* 40(0) 2(0) */
to: umode_t /* 102(0) 2(0) */
1 struct changed
[acme@newtoy net-2.6.20]$
I've prunned all the other offset changes, only this one is of interest here.
So now we have:
[acme@newtoy net-2.6.20]$ pahole --cacheline 64 ../OUTPUT/qemu/net-2.6.20/fs/inode.o inode
/* /pub/scm/linux/kernel/git/acme/net-2.6.20/include/linux/dcache.h:86 */
struct inode {
struct hlist_node i_hash; /* 0 8 */
struct list_head i_list; /* 8 8 */
struct list_head i_sb_list; /* 16 8 */
struct list_head i_dentry; /* 24 8 */
long unsigned int i_ino; /* 32 4 */
atomic_t i_count; /* 36 4 */
unsigned int i_nlink; /* 40 4 */
uid_t i_uid; /* 44 4 */
gid_t i_gid; /* 48 4 */
dev_t i_rdev; /* 52 4 */
loff_t i_size; /* 56 8 */
/* ---------- cacheline 1 boundary ---------- */
struct timespec i_atime; /* 64 8 */
struct timespec i_mtime; /* 72 8 */
struct timespec i_ctime; /* 80 8 */
unsigned int i_blkbits; /* 88 4 */
long unsigned int i_version; /* 92 4 */
blkcnt_t i_blocks; /* 96 4 */
short unsigned int i_bytes; /* 100 2 */
umode_t i_mode; /* 102 2 */
spinlock_t i_lock; /* 104 40 */
struct mutex i_mutex; /* 144 76 */
struct rw_semaphore i_alloc_sem; /* 220 64 */
struct inode_operations * i_op; /* 284 4 */
const struct file_operations * i_fop; /* 288 4 */
struct super_block * i_sb; /* 292 4 */
struct file_lock * i_flock; /* 296 4 */
struct address_space * i_mapping; /* 300 4 */
struct address_space i_data; /* 304 188 */
struct list_head i_devices; /* 492 8 */
union ; /* 500 4 */
int i_cindex; /* 504 4 */
__u32 i_generation; /* 508 4 */
/* ---------- cacheline 8 boundary ---------- */
long unsigned int i_dnotify_mask; /* 512 4 */
struct dnotify_struct * i_dnotify; /* 516 4 */
struct list_head inotify_watches; /* 520 8 */
struct mutex inotify_mutex; /* 528 76 */
long unsigned int i_state; /* 604 4 */
long unsigned int dirtied_when; /* 608 4 */
unsigned int i_flags; /* 612 4 */
atomic_t i_writecount; /* 616 4 */
void * i_security; /* 620 4 */
void * i_private; /* 624 4 */
}; /* size: 628 */
[acme@newtoy net-2.6.20]$
Signed-off-by: Arnaldo Carvalho de Melo <acme@mandriva.com>
Signed-off-by: Andrew Morton <akpm@osdl.org>
Signed-off-by: Linus Torvalds <torvalds@osdl.org>
Diffstat (limited to 'include')
| -rw-r--r-- | include/linux/fs.h | 2 |
1 files changed, 1 insertions, 1 deletions
diff --git a/include/linux/fs.h b/include/linux/fs.h index 3a1927e516d0..70b99fbb560b 100644 --- a/include/linux/fs.h +++ b/include/linux/fs.h @@ -543,7 +543,6 @@ struct inode { struct list_head i_dentry; unsigned long i_ino; atomic_t i_count; - umode_t i_mode; unsigned int i_nlink; uid_t i_uid; gid_t i_gid; @@ -559,6 +558,7 @@ struct inode { unsigned int i_blkbits; blkcnt_t i_blocks; unsigned short i_bytes; + umode_t i_mode; spinlock_t i_lock; /* i_blocks, i_bytes, maybe i_size */ struct mutex i_mutex; struct rw_semaphore i_alloc_sem; |