On Mon 18-11-24 01:20:24, Mateusz Guzik wrote:
> Notabaly occupied by lookup, get_link and permission.
>
> This pushes unlink to another cache line, otherwise the layout is the
> same on that front.
>
> Signed-off-by: Mateusz Guzik <mjguzik@xxxxxxxxx>
> ---
>
> Probably more can be done to rearrange struct. If someone is down to do
> it, I'm happy with this patch being dropped.
This makes some sense to me although I'd like to establish some higher
level guidelines (and document them in a comment) about what goes where in
the inode_operations struct. A lot of accesses to inode->i_op actually do
get optimized away with inode->i_opflags (e.g. frequent stuff like
.permission or .get_inode_acl) so there are actually high chances there's
only one access to inode->i_op for the operation we are doing and in such
case the ordering inside inode_operations doesn't really matter (it's
likely cache cold anyway). So I'm somewhat uncertain what the right
grouping should be and if it matters at all.
Honza
> diff --git a/include/linux/fs.h b/include/linux/fs.h
> index 7e29433c5ecc..972147da71f9 100644
> --- a/include/linux/fs.h
> +++ b/include/linux/fs.h
> @@ -2140,6 +2140,8 @@ struct inode_operations {
> const char * (*get_link) (struct dentry *, struct inode *, struct delayed_call *);
> int (*permission) (struct mnt_idmap *, struct inode *, int);
> struct posix_acl * (*get_inode_acl)(struct inode *, int, bool);
> + int (*getattr) (struct mnt_idmap *, const struct path *,
> + struct kstat *, u32, unsigned int);
>
> int (*readlink) (struct dentry *, char __user *,int);
>
> @@ -2157,8 +2159,6 @@ struct inode_operations {
> int (*rename) (struct mnt_idmap *, struct inode *, struct dentry *,
> struct inode *, struct dentry *, unsigned int);
> int (*setattr) (struct mnt_idmap *, struct dentry *, struct iattr *);
> - int (*getattr) (struct mnt_idmap *, const struct path *,
> - struct kstat *, u32, unsigned int);
> ssize_t (*listxattr) (struct dentry *, char *, size_t);
> int (*fiemap)(struct inode *, struct fiemap_extent_info *, u64 start,
> u64 len);
> --
> 2.43.0
>
--
Jan Kara <jack@xxxxxxxx>
SUSE Labs, CR
