dc51616486
After the rwsem replaced the tree lock implementation, the extent buffer
got smaller but leaving some holes behind. By changing log_index type
and reordering, we can squeeze the size further to 240 bytes, measured on
release config on x86_64. Log_index spans only 3 values and needs to be
signed.
Before:
struct extent_buffer {
u64 start; /* 0 8 */
long unsigned int len; /* 8 8 */
long unsigned int bflags; /* 16 8 */
struct btrfs_fs_info * fs_info; /* 24 8 */
spinlock_t refs_lock; /* 32 4 */
atomic_t refs; /* 36 4 */
atomic_t io_pages; /* 40 4 */
int read_mirror; /* 44 4 */
struct callback_head callback_head __attribute__((__aligned__(8))); /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
pid_t lock_owner; /* 64 4 */
bool lock_recursed; /* 68 1 */
/* XXX 3 bytes hole, try to pack */
struct rw_semaphore lock; /* 72 40 */
short int log_index; /* 112 2 */
/* XXX 6 bytes hole, try to pack */
struct page * pages[16]; /* 120 128 */
/* size: 248, cachelines: 4, members: 14 */
/* sum members: 239, holes: 2, sum holes: 9 */
/* forced alignments: 1 */
/* last cacheline: 56 bytes */
} __attribute__((__aligned__(8)));
After:
struct extent_buffer {
u64 start; /* 0 8 */
long unsigned int len; /* 8 8 */
long unsigned int bflags; /* 16 8 */
struct btrfs_fs_info * fs_info; /* 24 8 */
spinlock_t refs_lock; /* 32 4 */
atomic_t refs; /* 36 4 */
atomic_t io_pages; /* 40 4 */
int read_mirror; /* 44 4 */
struct callback_head callback_head __attribute__((__aligned__(8))); /* 48 16 */
/* --- cacheline 1 boundary (64 bytes) --- */
pid_t lock_owner; /* 64 4 */
bool lock_recursed; /* 68 1 */
s8 log_index; /* 69 1 */
/* XXX 2 bytes hole, try to pack */
struct rw_semaphore lock; /* 72 40 */
struct page * pages[16]; /* 112 128 */
/* size: 240, cachelines: 4, members: 14 */
/* sum members: 238, holes: 1, sum holes: 2 */
/* forced alignments: 1 */
/* last cacheline: 48 bytes */
} __attribute__((__aligned__(8)));
Reviewed-by: Josef Bacik <josef@toxicpanda.com>
Signed-off-by: David Sterba <dsterba@suse.com>
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| .. | ||
| 9p | ||
| adfs | ||
| affs | ||
| afs | ||
| autofs | ||
| befs | ||
| bfs | ||
| btrfs | ||
| cachefiles | ||
| ceph | ||
| cifs | ||
| coda | ||
| configfs | ||
| cramfs | ||
| crypto | ||
| debugfs | ||
| devpts | ||
| dlm | ||
| ecryptfs | ||
| efivarfs | ||
| efs | ||
| erofs | ||
| exfat | ||
| exportfs | ||
| ext2 | ||
| ext4 | ||
| f2fs | ||
| fat | ||
| freevxfs | ||
| fscache | ||
| fuse | ||
| gfs2 | ||
| hfs | ||
| hfsplus | ||
| hostfs | ||
| hpfs | ||
| hugetlbfs | ||
| iomap | ||
| isofs | ||
| jbd2 | ||
| jffs2 | ||
| jfs | ||
| kernfs | ||
| lockd | ||
| minix | ||
| nfs | ||
| nfs_common | ||
| nfsd | ||
| nilfs2 | ||
| nls | ||
| notify | ||
| ntfs | ||
| ocfs2 | ||
| omfs | ||
| openpromfs | ||
| orangefs | ||
| overlayfs | ||
| proc | ||
| pstore | ||
| qnx4 | ||
| qnx6 | ||
| quota | ||
| ramfs | ||
| reiserfs | ||
| romfs | ||
| squashfs | ||
| sysfs | ||
| sysv | ||
| tracefs | ||
| ubifs | ||
| udf | ||
| ufs | ||
| unicode | ||
| vboxsf | ||
| verity | ||
| xfs | ||
| zonefs | ||
| Kconfig | ||
| Kconfig.binfmt | ||
| Makefile | ||
| aio.c | ||
| anon_inodes.c | ||
| attr.c | ||
| bad_inode.c | ||
| binfmt_aout.c | ||
| binfmt_elf.c | ||
| binfmt_elf_fdpic.c | ||
| binfmt_em86.c | ||
| binfmt_flat.c | ||
| binfmt_misc.c | ||
| binfmt_script.c | ||
| block_dev.c | ||
| buffer.c | ||
| char_dev.c | ||
| compat_binfmt_elf.c | ||
| coredump.c | ||
| d_path.c | ||
| dax.c | ||
| dcache.c | ||
| dcookies.c | ||
| direct-io.c | ||
| drop_caches.c | ||
| eventfd.c | ||
| eventpoll.c | ||
| exec.c | ||
| fcntl.c | ||
| fhandle.c | ||
| file.c | ||
| file_table.c | ||
| filesystems.c | ||
| fs-writeback.c | ||
| fs_context.c | ||
| fs_parser.c | ||
| fs_pin.c | ||
| fs_struct.c | ||
| fs_types.c | ||
| fsopen.c | ||
| init.c | ||
| inode.c | ||
| internal.h | ||
| io-wq.c | ||
| io-wq.h | ||
| io_uring.c | ||
| ioctl.c | ||
| kernel_read_file.c | ||
| libfs.c | ||
| locks.c | ||
| mbcache.c | ||
| mount.h | ||
| mpage.c | ||
| namei.c | ||
| namespace.c | ||
| no-block.c | ||
| nsfs.c | ||
| open.c | ||
| pipe.c | ||
| pnode.c | ||
| pnode.h | ||
| posix_acl.c | ||
| proc_namespace.c | ||
| read_write.c | ||
| readdir.c | ||
| remap_range.c | ||
| select.c | ||
| seq_file.c | ||
| signalfd.c | ||
| splice.c | ||
| stack.c | ||
| stat.c | ||
| statfs.c | ||
| super.c | ||
| sync.c | ||
| timerfd.c | ||
| userfaultfd.c | ||
| utimes.c | ||
| xattr.c | ||