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authorPeter Zijlstra <a.p.zijlstra@chello.nl>2007-10-16 23:25:50 -0700
committerLinus Torvalds <torvalds@woody.linux-foundation.org>2007-10-17 08:42:45 -0700
commit3e26c149c358529b1605f8959341d34bc4b880a3 (patch)
tree9d173b1753b86bcf03a8591e2509e3162234447c /mm
parent04fbfdc14e5f48463820d6b9807daa5e9c92c51f (diff)
mm: dirty balancing for tasks
Based on ideas of Andrew: http://marc.info/?l=linux-kernel&m=102912915020543&w=2 Scale the bdi dirty limit inversly with the tasks dirty rate. This makes heavy writers have a lower dirty limit than the occasional writer. Andrea proposed something similar: http://lwn.net/Articles/152277/ The main disadvantage to his patch is that he uses an unrelated quantity to measure time, which leaves him with a workload dependant tunable. Other than that the two approaches appear quite similar. [akpm@linux-foundation.org: fix warning] Signed-off-by: Peter Zijlstra <a.p.zijlstra@chello.nl> Signed-off-by: Andrew Morton <akpm@linux-foundation.org> Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Diffstat (limited to 'mm')
-rw-r--r--mm/page-writeback.c50
1 files changed, 49 insertions, 1 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index b0360546ac8..4073d531cd7 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -118,6 +118,7 @@ static void background_writeout(unsigned long _min_pages);
*
*/
static struct prop_descriptor vm_completions;
+static struct prop_descriptor vm_dirties;
static unsigned long determine_dirtyable_memory(void);
@@ -146,6 +147,7 @@ int dirty_ratio_handler(struct ctl_table *table, int write,
if (ret == 0 && write && vm_dirty_ratio != old_ratio) {
int shift = calc_period_shift();
prop_change_shift(&vm_completions, shift);
+ prop_change_shift(&vm_dirties, shift);
}
return ret;
}
@@ -159,6 +161,11 @@ static inline void __bdi_writeout_inc(struct backing_dev_info *bdi)
__prop_inc_percpu(&vm_completions, &bdi->completions);
}
+static inline void task_dirty_inc(struct task_struct *tsk)
+{
+ prop_inc_single(&vm_dirties, &tsk->dirties);
+}
+
/*
* Obtain an accurate fraction of the BDI's portion.
*/
@@ -198,6 +205,37 @@ clip_bdi_dirty_limit(struct backing_dev_info *bdi, long dirty, long *pbdi_dirty)
*pbdi_dirty = min(*pbdi_dirty, avail_dirty);
}
+static inline void task_dirties_fraction(struct task_struct *tsk,
+ long *numerator, long *denominator)
+{
+ prop_fraction_single(&vm_dirties, &tsk->dirties,
+ numerator, denominator);
+}
+
+/*
+ * scale the dirty limit
+ *
+ * task specific dirty limit:
+ *
+ * dirty -= (dirty/8) * p_{t}
+ */
+void task_dirty_limit(struct task_struct *tsk, long *pdirty)
+{
+ long numerator, denominator;
+ long dirty = *pdirty;
+ u64 inv = dirty >> 3;
+
+ task_dirties_fraction(tsk, &numerator, &denominator);
+ inv *= numerator;
+ do_div(inv, denominator);
+
+ dirty -= inv;
+ if (dirty < *pdirty/2)
+ dirty = *pdirty/2;
+
+ *pdirty = dirty;
+}
+
/*
* Work out the current dirty-memory clamping and background writeout
* thresholds.
@@ -304,6 +342,7 @@ get_dirty_limits(long *pbackground, long *pdirty, long *pbdi_dirty,
*pbdi_dirty = bdi_dirty;
clip_bdi_dirty_limit(bdi, dirty, pbdi_dirty);
+ task_dirty_limit(current, pbdi_dirty);
}
}
@@ -720,6 +759,7 @@ void __init page_writeback_init(void)
shift = calc_period_shift();
prop_descriptor_init(&vm_completions, shift);
+ prop_descriptor_init(&vm_dirties, shift);
}
/**
@@ -998,7 +1038,7 @@ EXPORT_SYMBOL(redirty_page_for_writepage);
* If the mapping doesn't provide a set_page_dirty a_op, then
* just fall through and assume that it wants buffer_heads.
*/
-int fastcall set_page_dirty(struct page *page)
+static int __set_page_dirty(struct page *page)
{
struct address_space *mapping = page_mapping(page);
@@ -1016,6 +1056,14 @@ int fastcall set_page_dirty(struct page *page)
}
return 0;
}
+
+int fastcall set_page_dirty(struct page *page)
+{
+ int ret = __set_page_dirty(page);
+ if (ret)
+ task_dirty_inc(current);
+ return ret;
+}
EXPORT_SYMBOL(set_page_dirty);
/*