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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2008-04-30 07:54:36 (GMT)
committerLinus Torvalds <torvalds@linux-foundation.org>2008-04-30 15:29:50 (GMT)
commita42dde04152750426cc620fd277e80fffae2f65a (patch)
tree98cdf246280c59e0bf044ae6d2c229fc27b73203 /lib/proportions.c
parent189d3c4a94ef19fca2a71a6a336e9fda900e25e7 (diff)
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/proportions.c')
-rw-r--r--lib/proportions.c38
1 files changed, 32 insertions, 6 deletions
diff --git a/lib/proportions.c b/lib/proportions.c
index 9508d9a..4f387a6 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)

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