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 --- include/linux/backing-dev.h | 4 ++++ 1 file changed, 4 insertions(+) (limited to 'include') diff --git a/include/linux/backing-dev.h b/include/linux/backing-dev.h index 6d513666d45c..9a8965518d1d 100644 --- a/include/linux/backing-dev.h +++ b/include/linux/backing-dev.h @@ -51,6 +51,8 @@ struct backing_dev_info { struct prop_local_percpu completions; int dirty_exceeded; + unsigned int min_ratio; + struct device *dev; }; @@ -137,6 +139,8 @@ static inline unsigned long bdi_stat_error(struct backing_dev_info *bdi) #endif } +int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio); + /* * Flags in backing_dev_info::capability * - The first two flags control whether dirty pages will contribute to the -- cgit