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Based on kernel version 3.15.4. Page generated on 2014-07-07 08:59 EST.

1	What:		/sys/class/bdi/<bdi>/
2	Date:		January 2008
3	Contact:	Peter Zijlstra <a.p.zijlstra@chello.nl>
4	Description:
5	
6	Provide a place in sysfs for the backing_dev_info object.  This allows
7	setting and retrieving various BDI specific variables.
8	
9	The <bdi> identifier can be either of the following:
10	
11	MAJOR:MINOR
12	
13		Device number for block devices, or value of st_dev on
14		non-block filesystems which provide their own BDI, such as NFS
15		and FUSE.
16	
17	MAJOR:MINOR-fuseblk
18	
19		Value of st_dev on fuseblk filesystems.
20	
21	default
22	
23		The default backing dev, used for non-block device backed
24		filesystems which do not provide their own BDI.
25	
26	Files under /sys/class/bdi/<bdi>/
27	---------------------------------
28	
29	read_ahead_kb (read-write)
30	
31		Size of the read-ahead window in kilobytes
32	
33	min_ratio (read-write)
34	
35		Under normal circumstances each device is given a part of the
36		total write-back cache that relates to its current average
37		writeout speed in relation to the other devices.
38	
39		The 'min_ratio' parameter allows assigning a minimum
40		percentage of the write-back cache to a particular device.
41		For example, this is useful for providing a minimum QoS.
42	
43	max_ratio (read-write)
44	
45		Allows limiting a particular device to use not more than the
46		given percentage of the write-back cache.  This is useful in
47		situations where we want to avoid one device taking all or
48		most of the write-back cache.  For example in case of an NFS
49		mount that is prone to get stuck, or a FUSE mount which cannot
50		be trusted to play fair.
51	
52	stable_pages_required (read-only)
53	
54		If set, the backing device requires that all pages comprising a write
55		request must not be changed until writeout is complete.
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