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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-04-30 00:54:32 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 08:29:49 -0700
commitcf0ca9fe5dd9e3693d935757a7b2fc50fc576554 (patch)
treec795c5271eda9fc67579fa3176c646b892dfdb41 /Documentation/ABI/testing
parentcaafa4324335aeb11bc233d5f87aca8cce30beba (diff)
mm: bdi: export BDI attributes in sysfs
Provide a place in sysfs (/sys/class/bdi) for the backing_dev_info object. This allows us to see and set the various BDI specific variables. In particular this properly exposes the read-ahead window for all relevant users and /sys/block/<block>/queue/read_ahead_kb should be deprecated. With patient help from Kay Sievers and Greg KH [mszeredi@suse.cz] - split off NFS and FUSE changes into separate patches - document new sysfs attributes under Documentation/ABI - do bdi_class_init as a core_initcall, otherwise the "default" BDI won't be initialized - remove bdi_init_fmt macro, it's not used very much [akpm@linux-foundation.org: fix ia64 warning] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Cc: Kay Sievers <kay.sievers@vrfy.org> Acked-by: Greg KH <greg@kroah.com> Cc: Trond Myklebust <trond.myklebust@fys.uio.no> 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>
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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
+