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ext3: allocate ->s_blockgroup_lock separately

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As spotted by kmemtrace, struct ext3_sb_info is 17152 bytes on 64-bit
which makes it a very bad fit for SLAB allocators.  The culprit of the
wasted memory is ->s_blockgroup_lock which can be as big as 16 KB when
NR_CPUS >= 32.

To fix that, allocate ->s_blockgroup_lock, which fits nicely in a order 2
page in the worst case, separately.  This shinks down struct ext3_sb_info
enough to fit a 1 KB slab cache so now we allocate 16 KB + 1 KB instead of
32 KB saving 15 KB of memory.

Acked-by: Andreas Dilger <adilger@sun.com>
Signed-off-by: Pekka Enberg <penberg@cs.helsinki.fi>
Cc: <linux-ext4@vger.kernel.org>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
This commit is contained in:
Pekka Enberg 2009-01-07 18:07:25 -08:00 committed by Linus Torvalds
parent f420d4dc42
commit 5df096d67e
2 changed files with 11 additions and 3 deletions
Show stats Download patch file Download diff file Expand all files Collapse all files

10
fs/ext3/super.c
View file

@ -439,6 +439,7 @@ static void ext3_put_super (struct super_block * sb)
ext3_blkdev_remove(sbi);
}
sb->s_fs_info = NULL;
kfree(sbi->s_blockgroup_lock);
kfree(sbi);
return;
}
@ -1546,6 +1547,13 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
if (!sbi)
return -ENOMEM;
sbi->s_blockgroup_lock =
kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
if (!sbi->s_blockgroup_lock) {
kfree(sbi);
return -ENOMEM;
}
sb->s_fs_info = sbi;
sbi->s_mount_opt = 0;
sbi->s_resuid = EXT3_DEF_RESUID;
@ -1786,7 +1794,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
goto failed_mount;
}
bgl_lock_init(&sbi->s_blockgroup_lock);
bgl_lock_init(sbi->s_blockgroup_lock);
for (i = 0; i < db_count; i++) {
block = descriptor_loc(sb, logic_sb_block, i);

4
include/linux/ext3_fs_sb.h
View file

@ -60,7 +60,7 @@ struct ext3_sb_info {
struct percpu_counter s_freeblocks_counter;
struct percpu_counter s_freeinodes_counter;
struct percpu_counter s_dirs_counter;
struct blockgroup_lock s_blockgroup_lock;
struct blockgroup_lock *s_blockgroup_lock;
/* root of the per fs reservation window tree */
spinlock_t s_rsv_window_lock;
@ -86,7 +86,7 @@ struct ext3_sb_info {
static inline spinlock_t *
sb_bgl_lock(struct ext3_sb_info *sbi, unsigned int block_group)
{
return bgl_lock_ptr(&sbi->s_blockgroup_lock, block_group);
return bgl_lock_ptr(sbi->s_blockgroup_lock, block_group);
}
#endif /* _LINUX_EXT3_FS_SB */