This is an updated version of what had originally been an ext4-specific patch which significantly improves performance by lazily writing timestamp updates (and in particular, mtime updates) to disk. The in-memory timestamps are always correct, but they are only written to disk when required for correctness. This provides a huge performance boost for ext4 due to how it handles journalling, but it's valuable for all file systems running on flash storage or drive-managed SMR disks by reducing the metadata write load. So upon request, I've moved the functionality to the VFS layer. Once the /sbin/mount program adds support for MS_LAZYTIME, all file systems should be able to benefit from this optimization. There is still an ext4-specific optimization, which may be applicable for other file systems which store more than one inode in a block, but it will require file system specific code. It is purely optional, however. Please note the changes to update_time() and the new write_time() inode operations functions, which impact btrfs and xfs. The changes are fairly simple, but I would appreciate confirmation from the btrfs and xfs teams that I got things right. Thanks!! Theodore Ts'o (4): fs: split update_time() into update_time() and write_time() vfs: add support for a lazytime mount option vfs: don't let the dirty time inodes get more than a day stale ext4: add support for a lazytime mount option fs/btrfs/inode.c | 10 ++++++ fs/ext4/inode.c | 46 +++++++++++++++++++++++++- fs/ext4/super.c | 9 +++++ fs/fs-writeback.c | 39 +++++++++++++++++++++- fs/inode.c | 88 ++++++++++++++++++++++++++++++++++++++++++------- fs/proc_namespace.c | 1 + fs/sync.c | 7 ++++ fs/xfs/xfs_iops.c | 39 +++++++++------------- include/linux/fs.h | 5 +++ include/uapi/linux/fs.h | 1 + 10 files changed, 209 insertions(+), 36 deletions(-) -- 2.1.0 -- To unsubscribe from this list: send the line "unsubscribe linux-ext4" in the body of a message to majordomo@xxxxxxxxxxxxxxx More majordomo info at http://vger.kernel.org/majordomo-info.html
