0001 What: /sys/class/bdi/<bdi>/
0002 Date: January 2008
0003 Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
0004 Description:
0005
0006 Provide a place in sysfs for the backing_dev_info object. This allows
0007 setting and retrieving various BDI specific variables.
0008
0009 The <bdi> identifier can be either of the following:
0010
0011 MAJOR:MINOR
0012
0013 Device number for block devices, or value of st_dev on
0014 non-block filesystems which provide their own BDI, such as NFS
0015 and FUSE.
0016
0017 MAJOR:MINOR-fuseblk
0018
0019 Value of st_dev on fuseblk filesystems.
0020
0021 default
0022
0023 The default backing dev, used for non-block device backed
0024 filesystems which do not provide their own BDI.
0025
0026 What: /sys/class/bdi/<bdi>/read_ahead_kb
0027 Date: January 2008
0028 Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
0029 Description:
0030 Size of the read-ahead window in kilobytes
0031
0032 (read-write)
0033 What: /sys/class/bdi/<bdi>/min_ratio
0034 Date: January 2008
0035 Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
0036 Description:
0037 Under normal circumstances each device is given a part of the
0038 total write-back cache that relates to its current average
0039 writeout speed in relation to the other devices.
0040
0041 The 'min_ratio' parameter allows assigning a minimum
0042 percentage of the write-back cache to a particular device.
0043 For example, this is useful for providing a minimum QoS.
0044
0045 (read-write)
0046
0047 What: /sys/class/bdi/<bdi>/max_ratio
0048 Date: January 2008
0049 Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
0050 Description:
0051 Allows limiting a particular device to use not more than the
0052 given percentage of the write-back cache. This is useful in
0053 situations where we want to avoid one device taking all or
0054 most of the write-back cache. For example in case of an NFS
0055 mount that is prone to get stuck, or a FUSE mount which cannot
0056 be trusted to play fair.
0057
0058 (read-write)
0059 What: /sys/class/bdi/<bdi>/stable_pages_required
0060 Date: January 2008
0061 Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
0062 Description:
0063 If set, the backing device requires that all pages comprising a write
0064 request must not be changed until writeout is complete.
0065
0066 (read-only)
