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author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2008-04-30 00:54:35 -0700 |
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committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-30 08:29:50 -0700 |
commit | 189d3c4a94ef19fca2a71a6a336e9fda900e25e7 (patch) | |
tree | 75c0de871fe9922885a2fa073f15806d829342fa /mm/page-writeback.c | |
parent | b6f2fcbcfca9db2bd7aa24940224fcd3bbdbb8aa (diff) | |
download | kernel_samsung_smdk4412-189d3c4a94ef19fca2a71a6a336e9fda900e25e7.zip kernel_samsung_smdk4412-189d3c4a94ef19fca2a71a6a336e9fda900e25e7.tar.gz kernel_samsung_smdk4412-189d3c4a94ef19fca2a71a6a336e9fda900e25e7.tar.bz2 |
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/page-writeback.c')
-rw-r--r-- | mm/page-writeback.c | 27 |
1 files changed, 26 insertions, 1 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c index e5b6b11..4ac077f 100644 --- a/mm/page-writeback.c +++ b/mm/page-writeback.c @@ -243,6 +243,29 @@ static void task_dirty_limit(struct task_struct *tsk, long *pdirty) } /* + * + */ +static DEFINE_SPINLOCK(bdi_lock); +static unsigned int bdi_min_ratio; + +int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio) +{ + int ret = 0; + unsigned long flags; + + spin_lock_irqsave(&bdi_lock, flags); + min_ratio -= bdi->min_ratio; + if (bdi_min_ratio + min_ratio < 100) { + bdi_min_ratio += min_ratio; + bdi->min_ratio += min_ratio; + } else + ret = -EINVAL; + spin_unlock_irqrestore(&bdi_lock, flags); + + return ret; +} + +/* * Work out the current dirty-memory clamping and background writeout * thresholds. * @@ -330,7 +353,7 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty, *pdirty = dirty; if (bdi) { - u64 bdi_dirty = dirty; + u64 bdi_dirty; long numerator, denominator; /* @@ -338,8 +361,10 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty, */ bdi_writeout_fraction(bdi, &numerator, &denominator); + bdi_dirty = (dirty * (100 - bdi_min_ratio)) / 100; bdi_dirty *= numerator; do_div(bdi_dirty, denominator); + bdi_dirty += (dirty * bdi->min_ratio) / 100; *pbdi_dirty = bdi_dirty; clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty); |