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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2008-04-30 09:54:35 +0200 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-30 17:29:50 +0200 |
commit | 189d3c4a94ef19fca2a71a6a336e9fda900e25e7 (patch) | |
tree | 75c0de871fe9922885a2fa073f15806d829342fa /mm/backing-dev.c | |
parent | mm: bdi: expose the BDI object in sysfs for FUSE (diff) | |
download | linux-189d3c4a94ef19fca2a71a6a336e9fda900e25e7.tar.xz linux-189d3c4a94ef19fca2a71a6a336e9fda900e25e7.zip |
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.c | 21 |
1 files changed, 21 insertions, 0 deletions
diff --git a/mm/backing-dev.c b/mm/backing-dev.c index 847eabe4824c..4967fb176e53 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) |