diff options
Diffstat (limited to 'Documentation')
| -rw-r--r-- | Documentation/ABI/testing/sysfs-fs-f2fs | 16 | ||||
| -rw-r--r-- | Documentation/filesystems/f2fs.rst | 19 |
2 files changed, 35 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. diff --git a/Documentation/filesystems/f2fs.rst b/Documentation/filesystems/f2fs.rst index 6f3c6e91346d..d7b84695f56a 100644 --- a/Documentation/filesystems/f2fs.rst +++ b/Documentation/filesystems/f2fs.rst @@ -197,10 +197,29 @@ fault_type=%d Support configuring fault injection type, should be FAULT_DISCARD 0x000002000 FAULT_WRITE_IO 0x000004000 FAULT_SLAB_ALLOC 0x000008000 + FAULT_DQUOT_INIT 0x000010000 =================== =========== mode=%s Control block allocation mode which supports "adaptive" and "lfs". In "lfs" mode, there should be no random writes towards main area. + "fragment:segment" and "fragment:block" are newly added here. + These are developer options for experiments 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. + In "fragment:segment", f2fs allocates a new segment in ramdom + position. With this, we can simulate the after-GC condition. + In "fragment:block", we can scatter block allocation with + "max_fragment_chunk" and "max_fragment_hole" sysfs nodes. + We added some randomness to both chunk and hole size to make + it close to realistic IO pattern. So, in this mode, 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. With this, the newly + allocated blocks will be scattered throughout the whole partition. + Note that "fragment:block" implicitly enables "fragment:segment" + option for more randomness. + Please, use these options for your experiments and we strongly + recommend to re-format the filesystem after using these options. io_bits=%u Set the bit size of write IO requests. It should be set with "mode=lfs". usrquota Enable plain user disk quota accounting. |