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Date: Thu, 29 Nov 2007 12:14:18 +0100
From: Miklos Szeredi <miklos@...redi.hu>
To: a.p.zijlstra@...llo.nl
CC: fengguang.wu@...il.com, linux-kernel@...r.kernel.org
Subject: [patch 2/3] mm: bdi: allow to set a minimum to the bdi dirty limit
[mszeredi@...e.cz]
Fix parsing in min_ratio_store()
Signed-off-by: Peter Zijlstra <a.p.zijlstra@...llo.nl>
---
Index: linux/include/linux/backing-dev.h
===================================================================
--- linux.orig/include/linux/backing-dev.h 2007-11-26 17:24:19.000000000 +0100
+++ linux/include/linux/backing-dev.h 2007-11-26 17:24:39.000000000 +0100
@@ -51,6 +51,8 @@ struct backing_dev_info {
struct prop_local_percpu completions;
int dirty_exceeded;
+ unsigned int min_ratio;
+
struct device *dev;
};
@@ -147,6 +149,8 @@ static inline unsigned long bdi_stat_err
#endif
}
+int bdi_set_min_ratio(struct backing_dev_info *bdi, unsigned int min_ratio);
+
/*
* Flags in backing_dev_info::capability
* - The first two flags control whether dirty pages will contribute to the
Index: linux/mm/backing-dev.c
===================================================================
--- linux.orig/mm/backing-dev.c 2007-11-26 17:24:19.000000000 +0100
+++ linux/mm/backing-dev.c 2007-11-26 17:24:39.000000000 +0100
@@ -50,6 +50,24 @@ static inline unsigned long get_dirty(st
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[] = {
@@ -58,6 +76,7 @@ static struct device_attribute bdi_dev_a
__ATTR_RO(writeback_kb),
__ATTR_RO(dirty_kb),
__ATTR_RO(bdi_dirty_kb),
+ __ATTR_RW(min_ratio),
__ATTR_NULL,
};
@@ -199,3 +218,4 @@ long congestion_wait(int rw, long timeou
}
EXPORT_SYMBOL(congestion_wait);
+
Index: linux/mm/page-writeback.c
===================================================================
--- linux.orig/mm/page-writeback.c 2007-11-26 17:24:19.000000000 +0100
+++ linux/mm/page-writeback.c 2007-11-26 17:24:40.000000000 +0100
@@ -241,6 +241,29 @@ static void task_dirty_limit(struct task
}
/*
+ *
+ */
+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.
*
@@ -325,7 +348,7 @@ get_dirty_limits(long *pbackground, long
*pdirty = dirty;
if (bdi) {
- u64 bdi_dirty = dirty;
+ u64 bdi_dirty;
long numerator, denominator;
/*
@@ -333,8 +356,10 @@ get_dirty_limits(long *pbackground, long
*/
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);
-
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