linux/Documentation/ABI/testing/sysfs-class-bdi
Peter Zijlstra a42dde0415 mm: bdi: allow setting a maximum for the bdi dirty limit
Add "max_ratio" to /sys/class/bdi.  This indicates the maximum percentage of
the global dirty threshold allocated to this bdi.

[mszeredi@suse.cz]

 - fix parsing in max_ratio_store().
 - export bdi_set_max_ratio() to modules
 - limit bdi_dirty with bdi->max_ratio
 - document new sysfs attribute

Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl>
Signed-off-by: Miklos Szeredi <mszeredi@suse.cz>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
2008-04-30 08:29:50 -07:00

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What: /sys/class/bdi/<bdi>/
Date: January 2008
Contact: Peter Zijlstra <a.p.zijlstra@chello.nl>
Description:
Provide a place in sysfs for the backing_dev_info object.
This allows us to see and set the various BDI specific variables.
The <bdi> identifier can be either of the following:
MAJOR:MINOR
Device number for block devices, or value of st_dev on
non-block filesystems which provide their own BDI, such as NFS
and FUSE.
default
The default backing dev, used for non-block device backed
filesystems which do not provide their own BDI.
Files under /sys/class/bdi/<bdi>/
---------------------------------
read_ahead_kb (read-write)
Size of the read-ahead window in kilobytes
reclaimable_kb (read-only)
Reclaimable (dirty or unstable) memory destined for writeback
to this device
writeback_kb (read-only)
Memory currently under writeback to this device
dirty_kb (read-only)
Global threshold for reclaimable + writeback memory
bdi_dirty_kb (read-only)
Current threshold on this BDI for reclaimable + writeback
memory
min_ratio (read-write)
Minimal percentage of global dirty threshold allocated to this
bdi. If the value written to this file would make the the sum
of all min_ratio values exceed 100, then EINVAL is returned.
If min_ratio would become larger than the current max_ratio,
then also EINVAL is returned. The default is zero
max_ratio (read-write)
Maximal percentage of global dirty threshold allocated to this
bdi. If max_ratio would become smaller than the current
min_ratio, then EINVAL is returned. The default is 100