| Message ID | 270b9ad9e44ece857f8ec5fa006a484459c1fddd.1694126893.git.dsterba@suse.com (mailing list archive) |
|---|---|
| State | New, archived |
| Headers | show |
| Series | Cleanups and struct packing | expand |
On 2023/9/8 07:09, David Sterba wrote: > The values of level are bounded and fit into a byte so let's use it for > the structure to reduce size from 88 to 80 bytes on a release build, > which increases number of objects in the default 8K slab from 93 to 102. > > struct prelim_ref { > struct rb_node rbnode __attribute__((__aligned__(8))); /* 0 24 */ > u64 root_id; /* 24 8 */ > struct btrfs_key key_for_search; /* 32 17 */ > u8 level; /* 49 1 */ > > /* XXX 2 bytes hole, try to pack */ > > int count; /* 52 4 */ > struct extent_inode_elem * inode_list; /* 56 8 */ > /* --- cacheline 1 boundary (64 bytes) --- */ > u64 parent; /* 64 8 */ > u64 wanted_disk_byte; /* 72 8 */ > > /* size: 80, cachelines: 2, members: 8 */ > /* sum members: 78, holes: 1, sum holes: 2 */ > /* forced alignments: 1 */ > /* last cacheline: 16 bytes */ > } __attribute__((__aligned__(8))); > > Signed-off-by: David Sterba <dsterba@suse.com> Reviewed-by: Qu Wenruo <wqu@suse.com> Thanks, Qu > --- > fs/btrfs/backref.h | 2 +- > 1 file changed, 1 insertion(+), 1 deletion(-) > > diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h > index 1616e3e3f1e4..79742935399f 100644 > --- a/fs/btrfs/backref.h > +++ b/fs/btrfs/backref.h > @@ -247,7 +247,7 @@ struct prelim_ref { > struct rb_node rbnode; > u64 root_id; > struct btrfs_key key_for_search; > - int level; > + u8 level; > int count; > struct extent_inode_elem *inode_list; > u64 parent;
diff --git a/fs/btrfs/backref.h b/fs/btrfs/backref.h index 1616e3e3f1e4..79742935399f 100644 --- a/fs/btrfs/backref.h +++ b/fs/btrfs/backref.h @@ -247,7 +247,7 @@ struct prelim_ref { struct rb_node rbnode; u64 root_id; struct btrfs_key key_for_search; - int level; + u8 level; int count; struct extent_inode_elem *inode_list; u64 parent;
The values of level are bounded and fit into a byte so let's use it for the structure to reduce size from 88 to 80 bytes on a release build, which increases number of objects in the default 8K slab from 93 to 102. struct prelim_ref { struct rb_node rbnode __attribute__((__aligned__(8))); /* 0 24 */ u64 root_id; /* 24 8 */ struct btrfs_key key_for_search; /* 32 17 */ u8 level; /* 49 1 */ /* XXX 2 bytes hole, try to pack */ int count; /* 52 4 */ struct extent_inode_elem * inode_list; /* 56 8 */ /* --- cacheline 1 boundary (64 bytes) --- */ u64 parent; /* 64 8 */ u64 wanted_disk_byte; /* 72 8 */ /* size: 80, cachelines: 2, members: 8 */ /* sum members: 78, holes: 1, sum holes: 2 */ /* forced alignments: 1 */ /* last cacheline: 16 bytes */ } __attribute__((__aligned__(8))); Signed-off-by: David Sterba <dsterba@suse.com> --- fs/btrfs/backref.h | 2 +- 1 file changed, 1 insertion(+), 1 deletion(-)