1 What: /sys/fs/ext4/<disk>/mb_stats 1 What: /sys/fs/ext4/<disk>/mb_stats
2 Date: March 2008 2 Date: March 2008
3 Contact: "Theodore Ts'o" <tytso@mit.edu> 3 Contact: "Theodore Ts'o" <tytso@mit.edu>
4 Description: 4 Description:
5 Controls whether the multiblo 5 Controls whether the multiblock allocator should
6 collect statistics, which are 6 collect statistics, which are shown during the unmount.
7 1 means to collect statistics 7 1 means to collect statistics, 0 means not to collect
8 statistics 8 statistics
9 9
10 What: /sys/fs/ext4/<disk>/mb_group_p 10 What: /sys/fs/ext4/<disk>/mb_group_prealloc
11 Date: March 2008 11 Date: March 2008
12 Contact: "Theodore Ts'o" <tytso@mit.edu> 12 Contact: "Theodore Ts'o" <tytso@mit.edu>
13 Description: 13 Description:
14 The multiblock allocator will 14 The multiblock allocator will round up allocation
15 requests to a multiple of this 15 requests to a multiple of this tuning parameter if the
16 stripe size is not set in the 16 stripe size is not set in the ext4 superblock
17 17
18 What: /sys/fs/ext4/<disk>/mb_max_to_ 18 What: /sys/fs/ext4/<disk>/mb_max_to_scan
19 Date: March 2008 19 Date: March 2008
20 Contact: "Theodore Ts'o" <tytso@mit.edu> 20 Contact: "Theodore Ts'o" <tytso@mit.edu>
21 Description: 21 Description:
22 The maximum number of extents 22 The maximum number of extents the multiblock allocator
23 will search to find the best e 23 will search to find the best extent
24 24
25 What: /sys/fs/ext4/<disk>/mb_min_to_ 25 What: /sys/fs/ext4/<disk>/mb_min_to_scan
26 Date: March 2008 26 Date: March 2008
27 Contact: "Theodore Ts'o" <tytso@mit.edu> 27 Contact: "Theodore Ts'o" <tytso@mit.edu>
28 Description: 28 Description:
29 The minimum number of extents 29 The minimum number of extents the multiblock allocator
30 will search to find the best e 30 will search to find the best extent
31 31
32 What: /sys/fs/ext4/<disk>/mb_order2_ 32 What: /sys/fs/ext4/<disk>/mb_order2_req
33 Date: March 2008 33 Date: March 2008
34 Contact: "Theodore Ts'o" <tytso@mit.edu> 34 Contact: "Theodore Ts'o" <tytso@mit.edu>
35 Description: 35 Description:
36 Tuning parameter which control !! 36 Tuning parameter which controls the minimum size for
37 requests (as a power of 2) whe 37 requests (as a power of 2) where the buddy cache is
38 used 38 used
39 39
40 What: /sys/fs/ext4/<disk>/mb_stream_ 40 What: /sys/fs/ext4/<disk>/mb_stream_req
41 Date: March 2008 41 Date: March 2008
42 Contact: "Theodore Ts'o" <tytso@mit.edu> 42 Contact: "Theodore Ts'o" <tytso@mit.edu>
43 Description: 43 Description:
44 Files which have fewer blocks 44 Files which have fewer blocks than this tunable
45 parameter will have their bloc 45 parameter will have their blocks allocated out of a
46 block group specific prealloca 46 block group specific preallocation pool, so that small
47 files are packed closely toget 47 files are packed closely together. Each large file
48 will have its blocks allocated !! 48 will have its blocks allocated out of its own unique
49 preallocation pool. !! 49 preallocation pool.
50 50
51 What: /sys/fs/ext4/<disk>/inode_read 51 What: /sys/fs/ext4/<disk>/inode_readahead_blks
52 Date: March 2008 52 Date: March 2008
53 Contact: "Theodore Ts'o" <tytso@mit.edu> 53 Contact: "Theodore Ts'o" <tytso@mit.edu>
54 Description: 54 Description:
55 Tuning parameter which control 55 Tuning parameter which controls the maximum number of
56 inode table blocks that ext4's 56 inode table blocks that ext4's inode table readahead
57 algorithm will pre-read into t 57 algorithm will pre-read into the buffer cache
58 58
59 What: /sys/fs/ext4/<disk>/delayed_al 59 What: /sys/fs/ext4/<disk>/delayed_allocation_blocks
60 Date: March 2008 60 Date: March 2008
61 Contact: "Theodore Ts'o" <tytso@mit.edu> 61 Contact: "Theodore Ts'o" <tytso@mit.edu>
62 Description: 62 Description:
63 This file is read-only and sho 63 This file is read-only and shows the number of blocks
64 that are dirty in the page cac 64 that are dirty in the page cache, but which do not
65 have their location in the fil 65 have their location in the filesystem allocated yet.
66 66
67 What: /sys/fs/ext4/<disk>/lifetime_w 67 What: /sys/fs/ext4/<disk>/lifetime_write_kbytes
68 Date: March 2008 68 Date: March 2008
69 Contact: "Theodore Ts'o" <tytso@mit.edu> 69 Contact: "Theodore Ts'o" <tytso@mit.edu>
70 Description: 70 Description:
71 This file is read-only and sho 71 This file is read-only and shows the number of kilobytes
72 of data that have been written 72 of data that have been written to this filesystem since it was
73 created. 73 created.
74 74
75 What: /sys/fs/ext4/<disk>/session_wr 75 What: /sys/fs/ext4/<disk>/session_write_kbytes
76 Date: March 2008 76 Date: March 2008
77 Contact: "Theodore Ts'o" <tytso@mit.edu> 77 Contact: "Theodore Ts'o" <tytso@mit.edu>
78 Description: 78 Description:
79 This file is read-only and sho 79 This file is read-only and shows the number of
80 kilobytes of data that have be 80 kilobytes of data that have been written to this
81 filesystem since it was mounte 81 filesystem since it was mounted.
82 82
83 What: /sys/fs/ext4/<disk>/inode_goal 83 What: /sys/fs/ext4/<disk>/inode_goal
84 Date: June 2008 84 Date: June 2008
85 Contact: "Theodore Ts'o" <tytso@mit.edu> 85 Contact: "Theodore Ts'o" <tytso@mit.edu>
86 Description: 86 Description:
87 Tuning parameter which (if non 87 Tuning parameter which (if non-zero) controls the goal
88 inode used by the inode alloca 88 inode used by the inode allocator in preference to
89 all other allocation heuristic 89 all other allocation heuristics. This is intended for
90 debugging use only, and should 90 debugging use only, and should be 0 on production
91 systems. 91 systems.
92 92
93 What: /sys/fs/ext4/<disk>/max_writeb 93 What: /sys/fs/ext4/<disk>/max_writeback_mb_bump
94 Date: September 2009 94 Date: September 2009
95 Contact: "Theodore Ts'o" <tytso@mit.edu> 95 Contact: "Theodore Ts'o" <tytso@mit.edu>
96 Description: 96 Description:
97 The maximum number of megabyte 97 The maximum number of megabytes the writeback code will
98 try to write out before move o 98 try to write out before move on to another inode.
99 99
100 What: /sys/fs/ext4/<disk>/extent_max 100 What: /sys/fs/ext4/<disk>/extent_max_zeroout_kb
101 Date: August 2012 101 Date: August 2012
102 Contact: "Theodore Ts'o" <tytso@mit.edu> 102 Contact: "Theodore Ts'o" <tytso@mit.edu>
103 Description: 103 Description:
104 The maximum number of kilobyte 104 The maximum number of kilobytes which will be zeroed
105 out in preference to creating 105 out in preference to creating a new uninitialized
106 extent when manipulating an in 106 extent when manipulating an inode's extent tree. Note
107 that using a larger value will 107 that using a larger value will increase the
108 variability of time necessary 108 variability of time necessary to complete a random
109 write operation (since a 4k ra 109 write operation (since a 4k random write might turn
110 into a much larger write due t 110 into a much larger write due to the zeroout
111 operation). 111 operation).
112 112
113 What: /sys/fs/ext4/<disk>/journal_ta 113 What: /sys/fs/ext4/<disk>/journal_task
114 Date: February 2019 114 Date: February 2019
115 Contact: "Theodore Ts'o" <tytso@mit.edu> 115 Contact: "Theodore Ts'o" <tytso@mit.edu>
116 Description: 116 Description:
117 This file is read-only and sho 117 This file is read-only and shows the pid of journal thread in
118 current pid-namespace or 0 if 118 current pid-namespace or 0 if task is unreachable.
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