2023-04-21 01:49:36

by Noah Goldstein

Subject: [PATCH v1] ext4: move `ext4_count_free` to ext4.h so it can be easily inlined

`ext4_count_free` is a one-line helper that is clearly better off
being inlined. This saves a handful instructions in `vmlinux` on x86.

Instruction estimates use `wc -l` on `objdump`
Before: 8539271
After : 8539248

So saves roughly 20 instructions

Signed-off-by: Noah Goldstein <[email protected]>
---
fs/ext4/bitmap.c | 5 -----
fs/ext4/ext4.h | 6 +++++-
2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index f63e028c638c..c3cd2b878bbd 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -11,11 +11,6 @@
#include <linux/buffer_head.h>
#include "ext4.h"

-unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
-{
- return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
-}
-
int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 08b29c289da4..6e1d3c175a70 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2675,7 +2675,11 @@ struct mmpd_data {
# define NORET_AND noreturn,

/* bitmap.c */
-extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);
+static inline unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
+{
+ return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
+}
+
void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz);
--
2.34.1

2023-04-24 18:35:41

by Noah Goldstein

Subject: [PATCH v2] ext4: move `ext4_count_free` to ext4.h so it can be easily inlined

`ext4_count_free` is a one-line helper that is clearly better off
being inlined. This saves a handful instructions in `vmlinux` on x86.

Instruction estimates use `wc -l` on `objdump`
Before: 8539271
After : 8539248

So saves roughly 20 instructions

Signed-off-by: Noah Goldstein <[email protected]>
Reviewed-by: Jan Kara <[email protected]>
---
fs/ext4/bitmap.c | 5 -----
fs/ext4/ext4.h | 6 +++++-
2 files changed, 5 insertions(+), 6 deletions(-)

diff --git a/fs/ext4/bitmap.c b/fs/ext4/bitmap.c
index f63e028c638c..c3cd2b878bbd 100644
--- a/fs/ext4/bitmap.c
+++ b/fs/ext4/bitmap.c
@@ -11,11 +11,6 @@
#include <linux/buffer_head.h>
#include "ext4.h"

-unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
-{
- return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
-}
-
int ext4_inode_bitmap_csum_verify(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz)
diff --git a/fs/ext4/ext4.h b/fs/ext4/ext4.h
index 08b29c289da4..6e1d3c175a70 100644
--- a/fs/ext4/ext4.h
+++ b/fs/ext4/ext4.h
@@ -2675,7 +2675,11 @@ struct mmpd_data {
# define NORET_AND noreturn,

/* bitmap.c */
-extern unsigned int ext4_count_free(char *bitmap, unsigned numchars);
+static inline unsigned int ext4_count_free(char *bitmap, unsigned int numchars)
+{
+ return numchars * BITS_PER_BYTE - memweight(bitmap, numchars);
+}
+
void ext4_inode_bitmap_csum_set(struct super_block *sb, ext4_group_t group,
struct ext4_group_desc *gdp,
struct buffer_head *bh, int sz);
--
2.34.1