linux/Documentation/ABI/testing/sysfs-fs-ext4
Lukas Czerner 6f9524e9e1 ext4: update ext4 documentation
Add documentation for mount options and ioctls to
Documentation/filesystem/ext4.txt, which has not been udpated for some
time.  Also add for ext4 sysfs tunables to the
Documentation/ABI/testing/sysfs-fs-ext4 file, and fix a few
typographical errors in that file.

https://bugzilla.kernel.org/show_bug.cgi?id=9423

Signed-off-by: Lukas Czerner <lczerner@redhat.com>
Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
2011-02-21 20:16:21 -05:00

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What: /sys/fs/ext4/<disk>/mb_stats
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Controls whether the multiblock allocator should
collect statistics, which are shown during the unmount.
1 means to collect statistics, 0 means not to collect
statistics
What: /sys/fs/ext4/<disk>/mb_group_prealloc
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The multiblock allocator will round up allocation
requests to a multiple of this tuning parameter if the
stripe size is not set in the ext4 superblock
What: /sys/fs/ext4/<disk>/mb_max_to_scan
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The maximum number of extents the multiblock allocator
will search to find the best extent
What: /sys/fs/ext4/<disk>/mb_min_to_scan
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The minimum number of extents the multiblock allocator
will search to find the best extent
What: /sys/fs/ext4/<disk>/mb_order2_req
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Tuning parameter which controls the minimum size for
requests (as a power of 2) where the buddy cache is
used
What: /sys/fs/ext4/<disk>/mb_stream_req
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Files which have fewer blocks than this tunable
parameter will have their blocks allocated out of a
block group specific preallocation pool, so that small
files are packed closely together. Each large file
will have its blocks allocated out of its own unique
preallocation pool.
What: /sys/fs/ext4/<disk>/inode_readahead_blks
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Tuning parameter which controls the maximum number of
inode table blocks that ext4's inode table readahead
algorithm will pre-read into the buffer cache
What: /sys/fs/ext4/<disk>/delayed_allocation_blocks
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
This file is read-only and shows the number of blocks
that are dirty in the page cache, but which do not
have their location in the filesystem allocated yet.
What: /sys/fs/ext4/<disk>/lifetime_write_kbytes
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
This file is read-only and shows the number of kilobytes
of data that have been written to this filesystem since it was
created.
What: /sys/fs/ext4/<disk>/session_write_kbytes
Date: March 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
This file is read-only and shows the number of
kilobytes of data that have been written to this
filesystem since it was mounted.
What: /sys/fs/ext4/<disk>/inode_goal
Date: June 2008
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
Tuning parameter which (if non-zero) controls the goal
inode used by the inode allocator in preference to
all other allocation heuristics. This is intended for
debugging use only, and should be 0 on production
systems.
What: /sys/fs/ext4/<disk>/max_writeback_mb_bump
Date: September 2009
Contact: "Theodore Ts'o" <tytso@mit.edu>
Description:
The maximum number of megabytes the writeback code will
try to write out before move on to another inode.