From 189d3c4a94ef19fca2a71a6a336e9fda900e25e7 Mon Sep 17 00:00:00 2001 From: Peter Zijlstra Date: Wed, 30 Apr 2008 00:54:35 -0700 Subject: 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 Signed-off-by: Miklos Szeredi Signed-off-by: Andrew Morton Signed-off-by: Linus Torvalds --- Documentation/ABI/testing/sysfs-class-bdi | 6 ++++++ 1 file changed, 6 insertions(+) (limited to 'Documentation') diff --git a/Documentation/ABI/testing/sysfs-class-bdi b/Documentation/ABI/testing/sysfs-class-bdi index b800cdda40b..b9e8a9368dc 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 -- cgit v1.2.3