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kernel/linux-imx6_3.14.28/Documentation/ABI/testing/sysfs-fs-ext4 3.69 KB
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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.
  
  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).