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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-04-30 00:54:35 -0700
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 08:29:50 -0700
commit189d3c4a94ef19fca2a71a6a336e9fda900e25e7 (patch)
tree75c0de871fe9922885a2fa073f15806d829342fa /Documentation
parentb6f2fcbcfca9db2bd7aa24940224fcd3bbdbb8aa (diff)
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mm: bdi: allow setting a minimum for the bdi dirty limit
Under normal circumstances each device is given a part of the total write-back cache that relates to its current avg writeout speed in relation to the other devices. min_ratio - allows one to assign a minimum portion of the write-back cache to a particular device. This is useful in situations where you might want to provide a minimum QoS. (One request for this feature came from flash based storage people who wanted to avoid writing out at all costs - they of course needed some pdflush hacks as well) max_ratio - allows one to assign a maximum portion of the dirty limit to a particular device. This is useful in situations where you want to avoid one device taking all or most of the write-back cache. Eg. an NFS mount that is prone to get stuck, or a FUSE mount which you don't trust to play fair. Add "min_ratio" to /sys/class/bdi. This indicates the minimum percentage of the global dirty threshold allocated to this bdi. [mszeredi@suse.cz] - fix parsing in min_ratio_store() - 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>
Diffstat (limited to 'Documentation')
-rw-r--r--Documentation/ABI/testing/sysfs-class-bdi6
1 files changed, 6 insertions, 0 deletions
diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi
index b800cdda40bb..b9e8a9368dc6 100644
--- a/Documentation/ABI/testing/sysfs-class-bdi
+++ b/Documentation/ABI/testing/sysfs-class-bdi
@@ -44,3 +44,9 @@ 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.
+ The default is zero