2023-04-24 16:30:44

by Jan Kara

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

On Thu 20-04-23 20:47:49, Noah Goldstein wrote:
> `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]>

Looks fine. Feel free to add:

Reviewed-by: Jan Kara <[email protected]>

Honza

> ---
> 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
>
--
Jan Kara <[email protected]>
SUSE Labs, CR

2023-04-24 18:36:23

by Noah Goldstein

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

On Mon, Apr 24, 2023 at 11:24 AM Jan Kara <[email protected]> wrote:
>
> On Thu 20-04-23 20:47:49, Noah Goldstein wrote:
> > `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]>
>
> Looks fine. Feel free to add:
>
> Reviewed-by: Jan Kara <[email protected]>
>
Done, thank you.

> Honza
>
> > ---
> > 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
> >
> --
> Jan Kara <[email protected]>
> SUSE Labs, CR