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Date: Thu, 2 Feb 2017 14:19:53 -0500
From: Johannes Weiner <hannes@...xchg.org>
To: Andrew Morton <akpm@...ux-foundation.org>
Cc: Mel Gorman <mgorman@...e.de>, Michal Hocko <mhocko@...e.com>,
Minchan Kim <minchan.kim@...il.com>,
Rik van Riel <riel@...hat.com>,
Hillf Danton <hillf.zj@...baba-inc.com>, linux-mm@...ck.org,
linux-kernel@...r.kernel.org
Subject: [PATCH 3/7] mm: vmscan: kick flushers when we encounter dirty pages on the LRU fix
Mention dirty expiration as a condition: we need dirty data that is too
recent for periodic flushing and not large enough for waking up limit
flushing. As per Mel.
Link: http://lkml.kernel.org/r/20170126174739.GA30636@cmpxchg.org
Signed-off-by: Johannes Weiner <hannes@...xchg.org>
Cc: Hillf Danton <hillf.zj@...baba-inc.com>
Cc: Mel Gorman <mgorman@...e.de>
Signed-off-by: Andrew Morton <akpm@...ux-foundation.org>
---
mm/vmscan.c | 16 ++++++++--------
1 file changed, 8 insertions(+), 8 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 56ea8d24041f..83c92b866afe 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1799,14 +1799,14 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
/*
* If dirty pages are scanned that are not queued for IO, it
* implies that flushers are not doing their job. This can
- * happen when memory pressure pushes dirty pages to the end
- * of the LRU without the dirty limits being breached. It can
- * also happen when the proportion of dirty pages grows not
- * through writes but through memory pressure reclaiming all
- * the clean cache. And in some cases, the flushers simply
- * cannot keep up with the allocation rate. Nudge the flusher
- * threads in case they are asleep, but also allow kswapd to
- * start writing pages during reclaim.
+ * happen when memory pressure pushes dirty pages to the end of
+ * the LRU before the dirty limits are breached and the dirty
+ * data has expired. It can also happen when the proportion of
+ * dirty pages grows not through writes but through memory
+ * pressure reclaiming all the clean cache. And in some cases,
+ * the flushers simply cannot keep up with the allocation
+ * rate. Nudge the flusher threads in case they are asleep, but
+ * also allow kswapd to start writing pages during reclaim.
*/
if (stat.nr_unqueued_dirty == nr_taken) {
wakeup_flusher_threads(0, WB_REASON_VMSCAN);
--
2.11.0
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