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%)
We may get a little more by optimizing around the extra complexity
for > 64K blocks, but for now simply inlining is a nice improvement,
without a huge change in code size:
text data bss dec hex filename
314580 11888 176 326644 4fbf4 ext4-stock.ko
315246 11888 176 327310 4fe8e ext4-inlined.ko
Signed-off-by: Eric Sandeen <sandeen@xxxxxxxxxx>
---
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 19a4de5..8aba5b8 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -1378,6 +1378,31 @@ struct ext4_dir_entry_2 {
~EXT4_DIR_ROUND)
#define EXT4_MAX_REC_LEN ((1<<16)-1)
+static inline 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);
+}
+
+static inline __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));
+}
+
/*
* Hash Tree Directory indexing
* (c) Daniel Phillips, 2001
@@ -1601,8 +1626,6 @@ 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,
diff --git a/fs/ext4/namei.c b/fs/ext4/namei.c
index a43e661..77a7468 100644
--- a/fs/ext4/namei.c
+++ b/fs/ext4/namei.c
@@ -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
*/
--
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