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authorDaeho Jeong2021-09-29 11:12:03 -0700
committerJaegeuk Kim2021-10-26 14:04:30 -0700
commit6691d940b0e09dd1564130e7a354d6deaf05d009 (patch)
treeae609ea58abdfd7ce7c73e72f82d39226f2de3a9 /Documentation/ABI
parent84eab2a899f28137e51a36861ed2df9579f54ebe (diff)
f2fs: introduce fragment allocation mode mount option
Added two options into "mode=" mount option to make it possible for developers to simulate filesystem fragmentation/after-GC situation itself. The developers use these modes to understand filesystem fragmentation/after-GC condition well, and eventually get some insights to handle them better. "fragment:segment": f2fs allocates a new segment in ramdom position. With this, we can simulate the after-GC condition. "fragment:block" : We can scatter block allocation with "max_fragment_chunk" and "max_fragment_hole" sysfs nodes. f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole in the length of 1..<max_fragment_hole> by turns in a newly allocated free segment. Plus, this mode implicitly enables "fragment:segment" option for more randomness. Reviewed-by: Chao Yu <chao@kernel.org> Signed-off-by: Daeho Jeong <daehojeong@google.com> Signed-off-by: Jaegeuk Kim <jaegeuk@kernel.org>
Diffstat (limited to 'Documentation/ABI')
-rw-r--r--Documentation/ABI/testing/sysfs-fs-f2fs16
1 files changed, 16 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-fs-f2fs b/Documentation/ABI/testing/sysfs-fs-f2fs
index f627e705e663..b268e3e18b4a 100644
--- a/Documentation/ABI/testing/sysfs-fs-f2fs
+++ b/Documentation/ABI/testing/sysfs-fs-f2fs
@@ -512,3 +512,19 @@ Date: July 2021
Contact: "Daeho Jeong" <daehojeong@google.com>
Description: You can control the multiplier value of bdi device readahead window size
between 2 (default) and 256 for POSIX_FADV_SEQUENTIAL advise option.
+
+What: /sys/fs/f2fs/<disk>/max_fragment_chunk
+Date: August 2021
+Contact: "Daeho Jeong" <daehojeong@google.com>
+Description: With "mode=fragment:block" mount options, we can scatter block allocation.
+ f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole
+ in the length of 1..<max_fragment_hole> by turns. This value can be set
+ between 1..512 and the default value is 4.
+
+What: /sys/fs/f2fs/<disk>/max_fragment_hole
+Date: August 2021
+Contact: "Daeho Jeong" <daehojeong@google.com>
+Description: With "mode=fragment:block" mount options, we can scatter block allocation.
+ f2fs will allocate 1..<max_fragment_chunk> blocks in a chunk and make a hole
+ in the length of 1..<max_fragment_hole> by turns. This value can be set
+ between 1..512 and the default value is 4.