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Based on kernel version 3.16. Page generated on 2014-08-06 21:35 EST.

1	What:		/sys/fs/ext4/<disk>/mb_stats
2	Date:		March 2008
3	Contact:	"Theodore Ts'o" <tytso@mit.edu>
4	Description:
5			 Controls whether the multiblock allocator should
6			 collect statistics, which are shown during the unmount.
7			 1 means to collect statistics, 0 means not to collect
8			 statistics
9	
10	What:		/sys/fs/ext4/<disk>/mb_group_prealloc
11	Date:		March 2008
12	Contact:	"Theodore Ts'o" <tytso@mit.edu>
13	Description:
14			The multiblock allocator will round up allocation
15			requests to a multiple of this tuning parameter if the
16			stripe size is not set in the ext4 superblock
17	
18	What:		/sys/fs/ext4/<disk>/mb_max_to_scan
19	Date:		March 2008
20	Contact:	"Theodore Ts'o" <tytso@mit.edu>
21	Description:
22			The maximum number of extents the multiblock allocator
23			will search to find the best extent
24	
25	What:		/sys/fs/ext4/<disk>/mb_min_to_scan
26	Date:		March 2008
27	Contact:	"Theodore Ts'o" <tytso@mit.edu>
28	Description:
29			The minimum number of extents the multiblock allocator
30			will search to find the best extent
31	
32	What:		/sys/fs/ext4/<disk>/mb_order2_req
33	Date:		March 2008
34	Contact:	"Theodore Ts'o" <tytso@mit.edu>
35	Description:
36			Tuning parameter which controls the minimum size for 
37			requests (as a power of 2) where the buddy cache is
38			used
39	
40	What:		/sys/fs/ext4/<disk>/mb_stream_req
41	Date:		March 2008
42	Contact:	"Theodore Ts'o" <tytso@mit.edu>
43	Description:
44			Files which have fewer blocks than this tunable
45			parameter will have their blocks allocated out of a
46			block group specific preallocation pool, so that small
47			files are packed closely together.  Each large file
48			 will have its blocks allocated out of its own unique
49			 preallocation pool.
50	
51	What:		/sys/fs/ext4/<disk>/inode_readahead_blks
52	Date:		March 2008
53	Contact:	"Theodore Ts'o" <tytso@mit.edu>
54	Description:
55			Tuning parameter which controls the maximum number of
56			inode table blocks that ext4's inode table readahead
57			algorithm will pre-read into the buffer cache
58	
59	What:		/sys/fs/ext4/<disk>/delayed_allocation_blocks
60	Date:		March 2008
61	Contact:	"Theodore Ts'o" <tytso@mit.edu>
62	Description:
63			This file is read-only and shows the number of blocks
64			that are dirty in the page cache, but which do not
65			have their location in the filesystem allocated yet.
66	
67	What:		/sys/fs/ext4/<disk>/lifetime_write_kbytes
68	Date:		March 2008
69	Contact:	"Theodore Ts'o" <tytso@mit.edu>
70	Description:
71			This file is read-only and shows the number of kilobytes
72			of data that have been written to this filesystem since it was
73			created.
74	
75	What:		/sys/fs/ext4/<disk>/session_write_kbytes
76	Date:		March 2008
77	Contact:	"Theodore Ts'o" <tytso@mit.edu>
78	Description:
79			This file is read-only and shows the number of
80			kilobytes of data that have been written to this
81			filesystem since it was mounted.
82	
83	What:		/sys/fs/ext4/<disk>/inode_goal
84	Date:		June 2008
85	Contact:	"Theodore Ts'o" <tytso@mit.edu>
86	Description:
87			Tuning parameter which (if non-zero) controls the goal
88			inode used by the inode allocator in preference to
89			all other allocation heuristics.  This is intended for
90			debugging use only, and should be 0 on production
91			systems.
92	
93	What:		/sys/fs/ext4/<disk>/max_writeback_mb_bump
94	Date:		September 2009
95	Contact:	"Theodore Ts'o" <tytso@mit.edu>
96	Description:
97			The maximum number of megabytes the writeback code will
98			try to write out before move on to another inode.
99	
100	What:		/sys/fs/ext4/<disk>/extent_max_zeroout_kb
101	Date:		August 2012
102	Contact:	"Theodore Ts'o" <tytso@mit.edu>
103	Description:
104			The maximum number of kilobytes which will be zeroed
105			out in preference to creating a new uninitialized
106			extent when manipulating an inode's extent tree.  Note
107			that using a larger value will increase the
108			variability of time necessary to complete a random
109			write operation (since a 4k random write might turn
110			into a much larger write due to the zeroout
111			operation).
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