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Commit 0cfc9255 authored by Eric Sandeen's avatar Eric Sandeen Committed by Theodore Ts'o
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ext4: re-inline ext4_rec_len_(to|from)_disk functions 



commit 3d0518f4, "ext4: New rec_len encoding for very
large blocksizes" made several changes to this path, but from
a perf perspective, un-inlining ext4_rec_len_from_disk() seems
most significant.  This function is called from ext4_check_dir_entry(),
which on a file-creation workload is called extremely often.

I tested this with bonnie:

# bonnie++ -u root -s 0 -f -x 200 -d /mnt/test -n 32

(this does 200 iterations) and got this for the file creations:

ext4 stock:   Average =  21206.8 files/s
ext4 inlined: Average =  22346.7 files/s  (+5%)

Signed-off-by: default avatarEric Sandeen <sandeen@redhat.com>
Signed-off-by: default avatar"Theodore Ts'o" <tytso@mit.edu>
parent 8dd42046

fs/ext4/ext4.h

+37 −2
Original line number Diff line number Diff line
@@ -1411,6 +1411,43 @@ struct ext4_dir_entry_2 { 
					 ~EXT4_DIR_ROUND)

#define EXT4_MAX_REC_LEN		((1<<16)-1)



/*

 * If we ever get support for fs block sizes > page_size, we'll need

 * to remove the #if statements in the next two functions...

 */

static inline unsigned int

ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize)

{

	unsigned len = le16_to_cpu(dlen);



#if (PAGE_CACHE_SIZE >= 65536)

	if (len == EXT4_MAX_REC_LEN || len == 0)

		return blocksize;

	return (len & 65532) | ((len & 3) << 16);

#else

	return len;

#endif

}



static inline __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)

{

	if ((len > blocksize) || (blocksize > (1 << 18)) || (len & 3))

		BUG();

#if (PAGE_CACHE_SIZE >= 65536)

	if (len < 65536)

		return cpu_to_le16(len);

	if (len == blocksize) {

		if (blocksize == 65536)

			return cpu_to_le16(EXT4_MAX_REC_LEN);

		else

			return cpu_to_le16(0);

	}

	return cpu_to_le16((len & 65532) | ((len >> 16) & 3));

#else

	return cpu_to_le16(len);

#endif

}



/*

 * Hash Tree Directory indexing

 * (c) Daniel Phillips, 2001
@@ -1636,8 +1673,6 @@ extern long ext4_compat_ioctl(struct file *, unsigned int, unsigned long); 
extern int ext4_ext_migrate(struct inode *);



/* namei.c */

extern unsigned int ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize);

extern __le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize);

extern int ext4_orphan_add(handle_t *, struct inode *);

extern int ext4_orphan_del(handle_t *, struct inode *);

extern int ext4_htree_fill_tree(struct file *dir_file, __u32 start_hash,

fs/ext4/namei.c

+0 −24
Original line number Diff line number Diff line
@@ -179,30 +179,6 @@ static struct buffer_head * ext4_dx_find_entry(struct inode *dir, 
static int ext4_dx_add_entry(handle_t *handle, struct dentry *dentry,

			     struct inode *inode);



unsigned int ext4_rec_len_from_disk(__le16 dlen, unsigned blocksize)

{

	unsigned len = le16_to_cpu(dlen);



	if (len == EXT4_MAX_REC_LEN || len == 0)

		return blocksize;

	return (len & 65532) | ((len & 3) << 16);

}



__le16 ext4_rec_len_to_disk(unsigned len, unsigned blocksize)

{

	if ((len > blocksize) || (blocksize > (1 << 18)) || (len & 3))

		BUG();

	if (len < 65536)

		return cpu_to_le16(len);

	if (len == blocksize) {

		if (blocksize == 65536)

			return cpu_to_le16(EXT4_MAX_REC_LEN);

		else

			return cpu_to_le16(0);

	}

	return cpu_to_le16((len & 65532) | ((len >> 16) & 3));

}



/*

 * p is at least 6 bytes before the end of page

 */