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ext4: re-inline ext4_rec_len_(to|from)_disk functions

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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: Eric Sandeen <sandeen@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
This commit is contained in:
Eric Sandeen
2010-08-05 01:46:37 -04:00
committed by Theodore Ts'o
parent 8dd420466c
commit 0cfc9255a1
2 changed files with 37 additions and 26 deletions
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24
fs/ext4/namei.c
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@@ -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
*/