| From: |
| Max Kellermann <max.kellermann-AT-ionos.com> |
| To: |
| idryomov-AT-gmail.com, amarkuze-AT-redhat.com, ceph-devel-AT-vger.kernel.org, linux-kernel-AT-vger.kernel.org |
| Subject: |
| [PATCH 00/12] fs/ceph: optimize struct layouts |
| Date: |
| Fri, 12 Jun 2026 18:51:52 +0200 |
| Message-ID: |
| <20260612165204.86137-1-max.kellermann@ionos.com> |
| Cc: |
| Max Kellermann <max.kellermann-AT-ionos.com> |
| Archive-link: |
| Article |
This patch set aims to reduce the memory usage of the Ceph filesystems
by optimizing the layout of structs, most importantly struct
ceph_inode_info:
- use `bool` instead of `int` for booelans
- use `u32` instead of `u64` where possible
- reorder fields to eliminate padding holes
- eliminate redundant fields
Without this patch set, ceph_inode_info looks like this with pahole:
/* size: 1456, cachelines: 23, members: 78 */
/* sum members: 1424, holes: 8, sum holes: 32 */
/* member types with holes: 4, total: 4 */
With this patch set, struct ceph_inode_info got smaller by 96 bytes:
/* size: 1360, cachelines: 22, members: 75 */
/* member types with holes: 2, total: 2 */
Max Kellermann (12):
fs/ceph/super: remove unused field `i_cap_migration_resv`
fs/ceph/super: make field `i_truncate_pagecache_size` optional
include/ceph/ceph_fs.h: convert `pool_id` to u32
fs/ceph/super.h: convert ceph_inode_xattr fields to `bool`
fs/ceph/super.h: convert ceph_cap_snap.writing fields to `bool`
fs/ceph: consistently use `u32` for `time_warp_seq`
fs/ceph/super: reorder fields to eliminate padding holes
fs/ceph: remove i_truncate_mutex, use i_fragtree_mutex for both
fs/ceph/super.h: add `const` to helpers
fs/ceph/super.h: add helper ceph_in_snap()
fs/ceph: use ceph_vino() etc. instead of accessing i_vino directly
fs/ceph: remove redundant inode number from ceph_inode_info
fs/ceph/acl.c | 2 +-
fs/ceph/addr.c | 23 ++++----
fs/ceph/cache.c | 4 +-
fs/ceph/caps.c | 8 +--
fs/ceph/dir.c | 20 +++----
fs/ceph/export.c | 8 +--
fs/ceph/file.c | 28 +++++-----
fs/ceph/inode.c | 38 ++++++++-----
fs/ceph/mds_client.c | 12 ++---
fs/ceph/mds_client.h | 2 +-
fs/ceph/quota.c | 6 +--
fs/ceph/snap.c | 8 +--
fs/ceph/super.h | 102 +++++++++++++++++++++++++----------
fs/ceph/util.c | 8 +--
fs/ceph/xattr.c | 18 +++----
include/linux/ceph/ceph_fs.h | 2 +-
16 files changed, 171 insertions(+), 118 deletions(-)
--
2.47.3
