mirror of
https://github.com/team-infusion-developers/android_kernel_samsung_msm8976.git
synced 2024-11-01 10:33:27 +00:00
67a5da564f
Currently in ext4 the length of zero-out chunk is set to 7 file system blocks. But if an inode has uninitailized extents from using fallocate to preallocate space, and the workload issues many random writes, this can cause a fragmented extent tree that will unnecessarily grow the extent tree. So create a new sysfs tunable, extent_max_zeroout_kb, which controls the maximum size where blocks will be zeroed out instead of creating a new uninitialized extent. The default of this has been sent to 32kb. CC: Zach Brown <zab@zabbo.net> CC: Andreas Dilger <adilger@dilger.ca> Signed-off-by: Zheng Liu <wenqing.lz@taobao.com> Signed-off-by: "Theodore Ts'o" <tytso@mit.edu>
111 lines
3.7 KiB
Text
111 lines
3.7 KiB
Text
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.
|
|
|
|
What: /sys/fs/ext4/<disk>/extent_max_zeroout_kb
|
|
Date: August 2012
|
|
Contact: "Theodore Ts'o" <tytso@mit.edu>
|
|
Description:
|
|
The maximum number of kilobytes which will be zeroed
|
|
out in preference to creating a new uninitialized
|
|
extent when manipulating an inode's extent tree. Note
|
|
that using a larger value will increase the
|
|
variability of time necessary to complete a random
|
|
write operation (since a 4k random write might turn
|
|
into a much larger write due to the zeroout
|
|
operation).
|