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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 /mm/backing-dev.c
parentb6f2fcbcfca9db2bd7aa24940224fcd3bbdbb8aa (diff)
downloadconfigs-189d3c4a94ef19fca2a71a6a336e9fda900e25e7.tar.gz
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 'mm/backing-dev.c')
-rw-r--r--mm/backing-dev.c21
1 files changed, 21 insertions, 0 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c
index 847eabe4824..4967fb176e5 100644
--- a/mm/backing-dev.c
+++ b/mm/backing-dev.c
@@ -55,6 +55,24 @@ static inline unsigned long get_dirty(struct backing_dev_info *bdi, int i)
BDI_SHOW(dirty_kb, K(get_dirty(bdi, 1)))
BDI_SHOW(bdi_dirty_kb, K(get_dirty(bdi, 2)))
+static ssize_t min_ratio_store(struct device *dev,
+ struct device_attribute *attr, const char *buf, size_t count)
+{
+ struct backing_dev_info *bdi = dev_get_drvdata(dev);
+ char *end;
+ unsigned int ratio;
+ ssize_t ret = -EINVAL;
+
+ ratio = simple_strtoul(buf, &end, 10);
+ if (*buf && (end[0] == '\0' || (end[0] == '\n' && end[1] == '\0'))) {
+ ret = bdi_set_min_ratio(bdi, ratio);
+ if (!ret)
+ ret = count;
+ }
+ return ret;
+}
+BDI_SHOW(min_ratio, bdi->min_ratio)
+
#define __ATTR_RW(attr) __ATTR(attr, 0644, attr##_show, attr##_store)
static struct device_attribute bdi_dev_attrs[] = {
@@ -63,6 +81,7 @@ static struct device_attribute bdi_dev_attrs[] = {
__ATTR_RO(writeback_kb),
__ATTR_RO(dirty_kb),
__ATTR_RO(bdi_dirty_kb),
+ __ATTR_RW(min_ratio),
__ATTR_NULL,
};
@@ -127,6 +146,8 @@ int bdi_init(struct backing_dev_info *bdi)
bdi->dev = NULL;
+ bdi->min_ratio = 0;
+
for (i = 0; i < NR_BDI_STAT_ITEMS; i++) {
err = percpu_counter_init_irq(&bdi->bdi_stat[i], 0);
if (err)