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Date: Fri, 21 Nov 2014 14:59:20 -0500
From: Theodore Ts'o <tytso@....edu>
To: linux-fsdevel@...r.kernel.org
Cc: Ext4 Developers List <linux-ext4@...r.kernel.org>, xfs@....sgi.com,
linux-btrfs@...r.kernel.org, Theodore Ts'o <tytso@....edu>
Subject: [PATCH 0/4] add support for a lazytime mount option
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
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