writeback: make balance_dirty_pages() gradually back more off
Currently it just sleeps for a very short time, just 1 jiffy. If
we keep looping in there, continually delay for a little longer
of up to 100msec in total. That was the old limit for congestion
wait.
Signed-off-by: Jens Axboe <jens.axboe@oracle.com>
diff --git a/mm/page-writeback.c b/mm/page-writeback.c
index 2585349..d1ba464 100644
--- a/mm/page-writeback.c
+++ b/mm/page-writeback.c
@@ -485,6 +485,7 @@
unsigned long bdi_thresh;
unsigned long pages_written = 0;
unsigned long write_chunk = sync_writeback_pages();
+ unsigned long pause = 1;
struct backing_dev_info *bdi = mapping->backing_dev_info;
@@ -561,7 +562,15 @@
if (pages_written >= write_chunk)
break; /* We've done our duty */
- schedule_timeout_interruptible(1);
+ schedule_timeout_interruptible(pause);
+
+ /*
+ * Increase the delay for each loop, up to our previous
+ * default of taking a 100ms nap.
+ */
+ pause <<= 1;
+ if (pause > HZ / 10)
+ pause = HZ / 10;
}
if (bdi_nr_reclaimable + bdi_nr_writeback < bdi_thresh &&