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-rw-r--r--mm/page-writeback.c26
1 files changed, 20 insertions, 6 deletions
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index f9d9f5476d58..1d781803e629 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -281,12 +281,13 @@ static inline void task_dirties_fraction(struct task_struct *tsk,
* effectively curb the growth of dirty pages. Light dirtiers with high enough
* dirty threshold may never get throttled.
*/
+#define TASK_LIMIT_FRACTION 8
static unsigned long task_dirty_limit(struct task_struct *tsk,
unsigned long bdi_dirty)
{
long numerator, denominator;
unsigned long dirty = bdi_dirty;
- u64 inv = dirty >> 3;
+ u64 inv = dirty / TASK_LIMIT_FRACTION;
task_dirties_fraction(tsk, &numerator, &denominator);
inv *= numerator;
@@ -297,6 +298,12 @@ static unsigned long task_dirty_limit(struct task_struct *tsk,
return max(dirty, bdi_dirty/2);
}
+/* Minimum limit for any task */
+static unsigned long task_min_dirty_limit(unsigned long bdi_dirty)
+{
+ return bdi_dirty - bdi_dirty / TASK_LIMIT_FRACTION;
+}
+
/*
*
*/
@@ -651,9 +658,12 @@ static void balance_dirty_pages(struct address_space *mapping,
unsigned long background_thresh;
unsigned long dirty_thresh;
unsigned long bdi_thresh;
+ unsigned long task_bdi_thresh;
+ unsigned long min_task_bdi_thresh;
unsigned long pages_written = 0;
unsigned long pause = 1;
bool dirty_exceeded = false;
+ bool clear_dirty_exceeded = true;
struct backing_dev_info *bdi = mapping->backing_dev_info;
unsigned long start_time = jiffies;
@@ -673,7 +683,8 @@ static void balance_dirty_pages(struct address_space *mapping,
break;
bdi_thresh = bdi_dirty_limit(bdi, dirty_thresh);
- bdi_thresh = task_dirty_limit(current, bdi_thresh);
+ min_task_bdi_thresh = task_min_dirty_limit(bdi_thresh);
+ task_bdi_thresh = task_dirty_limit(current, bdi_thresh);
/*
* In order to avoid the stacked BDI deadlock we need
@@ -685,7 +696,7 @@ static void balance_dirty_pages(struct address_space *mapping,
* actually dirty; with m+n sitting in the percpu
* deltas.
*/
- if (bdi_thresh < 2*bdi_stat_error(bdi)) {
+ if (task_bdi_thresh < 2 * bdi_stat_error(bdi)) {
bdi_nr_reclaimable = bdi_stat_sum(bdi, BDI_RECLAIMABLE);
bdi_dirty = bdi_nr_reclaimable +
bdi_stat_sum(bdi, BDI_WRITEBACK);
@@ -701,8 +712,10 @@ static void balance_dirty_pages(struct address_space *mapping,
* bdi or process from holding back light ones; The latter is
* the last resort safeguard.
*/
- dirty_exceeded = (bdi_dirty > bdi_thresh) ||
+ dirty_exceeded = (bdi_dirty > task_bdi_thresh) ||
(nr_dirty > dirty_thresh);
+ clear_dirty_exceeded = (bdi_dirty <= min_task_bdi_thresh) &&
+ (nr_dirty <= dirty_thresh);
if (!dirty_exceeded)
break;
@@ -723,7 +736,7 @@ static void balance_dirty_pages(struct address_space *mapping,
* up.
*/
trace_balance_dirty_start(bdi);
- if (bdi_nr_reclaimable > bdi_thresh) {
+ if (bdi_nr_reclaimable > task_bdi_thresh) {
pages_written += writeback_inodes_wb(&bdi->wb,
write_chunk);
trace_balance_dirty_written(bdi, pages_written);
@@ -766,7 +779,8 @@ static void balance_dirty_pages(struct address_space *mapping,
pause = HZ / 10;
}
- if (!dirty_exceeded && bdi->dirty_exceeded)
+ /* Clear dirty_exceeded flag only when no task can exceed the limit */
+ if (clear_dirty_exceeded && bdi->dirty_exceeded)
bdi->dirty_exceeded = 0;
if (writeback_in_progress(bdi))