ext3: allocate ->s_blockgroup_lock separately
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>
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@ -439,6 +439,7 @@ static void ext3_put_super (struct super_block * sb)
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ext3_blkdev_remove(sbi);
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}
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sb->s_fs_info = NULL;
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kfree(sbi->s_blockgroup_lock);
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kfree(sbi);
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return;
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}
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@ -1546,6 +1547,13 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
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sbi = kzalloc(sizeof(*sbi), GFP_KERNEL);
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if (!sbi)
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return -ENOMEM;
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sbi->s_blockgroup_lock =
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kzalloc(sizeof(struct blockgroup_lock), GFP_KERNEL);
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if (!sbi->s_blockgroup_lock) {
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kfree(sbi);
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return -ENOMEM;
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}
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sb->s_fs_info = sbi;
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sbi->s_mount_opt = 0;
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sbi->s_resuid = EXT3_DEF_RESUID;
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@ -1786,7 +1794,7 @@ static int ext3_fill_super (struct super_block *sb, void *data, int silent)
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goto failed_mount;
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}
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bgl_lock_init(&sbi->s_blockgroup_lock);
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bgl_lock_init(sbi->s_blockgroup_lock);
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for (i = 0; i < db_count; i++) {
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block = descriptor_loc(sb, logic_sb_block, i);
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@ -60,7 +60,7 @@ struct ext3_sb_info {
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struct percpu_counter s_freeblocks_counter;
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struct percpu_counter s_freeinodes_counter;
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struct percpu_counter s_dirs_counter;
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struct blockgroup_lock s_blockgroup_lock;
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struct blockgroup_lock *s_blockgroup_lock;
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/* root of the per fs reservation window tree */
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spinlock_t s_rsv_window_lock;
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@ -86,7 +86,7 @@ struct ext3_sb_info {
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static inline spinlock_t *
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sb_bgl_lock(struct ext3_sb_info *sbi, unsigned int block_group)
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{
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return bgl_lock_ptr(&sbi->s_blockgroup_lock, block_group);
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return bgl_lock_ptr(sbi->s_blockgroup_lock, block_group);
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}
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#endif /* _LINUX_EXT3_FS_SB */
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