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| author | Peter Zijlstra <a.p.zijlstra@chello.nl> | 2008-04-30 00:54:36 -0700 |
|---|---|---|
| committer | Linus Torvalds <torvalds@linux-foundation.org> | 2008-04-30 08:29:50 -0700 |
| commit | a42dde04152750426cc620fd277e80fffae2f65a (patch) | |
| tree | 98cdf246280c59e0bf044ae6d2c229fc27b73203 /lib | |
| parent | 189d3c4a94ef19fca2a71a6a336e9fda900e25e7 (diff) | |
| download | lwn-a42dde04152750426cc620fd277e80fffae2f65a.tar.gz lwn-a42dde04152750426cc620fd277e80fffae2f65a.zip | |
mm: bdi: allow setting a maximum for the bdi dirty limit
Add "max_ratio" to /sys/class/bdi. This indicates the maximum percentage of
the global dirty threshold allocated to this bdi.
[mszeredi@suse.cz]
- fix parsing in max_ratio_store().
- export bdi_set_max_ratio() to modules
- limit bdi_dirty with bdi->max_ratio
- 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 'lib')
| -rw-r--r-- | lib/proportions.c | 38 |
1 files changed, 32 insertions, 6 deletions
diff --git a/lib/proportions.c b/lib/proportions.c index 9508d9a7af3e..4f387a643d72 100644 --- a/lib/proportions.c +++ b/lib/proportions.c @@ -73,12 +73,6 @@ #include <linux/proportions.h> #include <linux/rcupdate.h> -/* - * Limit the time part in order to ensure there are some bits left for the - * cycle counter. - */ -#define PROP_MAX_SHIFT (3*BITS_PER_LONG/4) - int prop_descriptor_init(struct prop_descriptor *pd, int shift) { int err; @@ -268,6 +262,38 @@ void __prop_inc_percpu(struct prop_descriptor *pd, struct prop_local_percpu *pl) } /* + * identical to __prop_inc_percpu, except that it limits this pl's fraction to + * @frac/PROP_FRAC_BASE by ignoring events when this limit has been exceeded. + */ +void __prop_inc_percpu_max(struct prop_descriptor *pd, + struct prop_local_percpu *pl, long frac) +{ + struct prop_global *pg = prop_get_global(pd); + + prop_norm_percpu(pg, pl); + + if (unlikely(frac != PROP_FRAC_BASE)) { + unsigned long period_2 = 1UL << (pg->shift - 1); + unsigned long counter_mask = period_2 - 1; + unsigned long global_count; + long numerator, denominator; + + numerator = percpu_counter_read_positive(&pl->events); + global_count = percpu_counter_read(&pg->events); + denominator = period_2 + (global_count & counter_mask); + + if (numerator > ((denominator * frac) >> PROP_FRAC_SHIFT)) + goto out_put; + } + + percpu_counter_add(&pl->events, 1); + percpu_counter_add(&pg->events, 1); + +out_put: + prop_put_global(pd, pg); +} + +/* * Obtain a fraction of this proportion * * p_{j} = x_{j} / (period/2 + t % period/2) |