f2fs: give an option to enable in-place-updates during fsync to users
If user wrote F2FS_IPU_FSYNC:4 in /sys/fs/f2fs/ipu_policy, f2fs_sync_file
only starts to try in-place-updates.
And, if the number of dirty pages is over /sys/fs/f2fs/min_fsync_blocks, it
keeps out-of-order manner. Otherwise, it triggers in-place-updates.
This may be used by storage showing very high random write performance.
For example, it can be used when,
Seq. writes (Data) + wait + Seq. writes (Node)
is pretty much slower than,
Rand. writes (Data)
Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index 62dd725..6f9157f 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -44,6 +44,13 @@
Controls the FS utilization condition for the in-place-update
policies.
+What: /sys/fs/f2fs/<disk>/min_fsync_blocks
+Date: September 2014
+Contact: "Jaegeuk Kim" <jaegeuk@kernel.org>
+Description:
+ Controls the dirty page count condition for the in-place-update
+ policies.
+
What: /sys/fs/f2fs/<disk>/max_small_discards
Date: November 2013
Contact: "Jaegeuk Kim" <jaegeuk.kim@samsung.com>
diff --git a/Documentation/filesystems/f2fs.txt b/Documentation/filesystems/f2fs.txt
index a2046a7..d010da8 100644
--- a/Documentation/filesystems/f2fs.txt
+++ b/Documentation/filesystems/f2fs.txt
@@ -194,13 +194,20 @@
updates in f2fs. There are five policies:
0: F2FS_IPU_FORCE, 1: F2FS_IPU_SSR,
2: F2FS_IPU_UTIL, 3: F2FS_IPU_SSR_UTIL,
- 4: F2FS_IPU_DISABLE.
+ 4: F2FS_IPU_FSYNC, 5: F2FS_IPU_DISABLE.
min_ipu_util This parameter controls the threshold to trigger
in-place-updates. The number indicates percentage
of the filesystem utilization, and used by
F2FS_IPU_UTIL and F2FS_IPU_SSR_UTIL policies.
+ min_fsync_blocks This parameter controls the threshold to trigger
+ in-place-updates when F2FS_IPU_FSYNC mode is set.
+ The number indicates the number of dirty pages
+ when fsync needs to flush on its call path. If
+ the number is less than this value, it triggers
+ in-place-updates.
+
max_victim_search This parameter controls the number of trials to
find a victim segment when conducting SSR and
cleaning operations. The default value is 4096