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Message-Id: <20231018082104.3918770-3-link@vivo.com>
Date: Wed, 18 Oct 2023 16:21:00 +0800
From: Huan Yang <link@...o.com>
To: Yu Zhao <yuzhao@...gle.com>, Steven Rostedt <rostedt@...dmis.org>,
Masami Hiramatsu <mhiramat@...nel.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Huan Yang <link@...o.com>,
Suren Baghdasaryan <surenb@...gle.com>,
Vlastimil Babka <vbabka@...e.cz>, linux-kernel@...r.kernel.org,
linux-trace-kernel@...r.kernel.org, linux-mm@...ck.org,
bpf@...r.kernel.org
Cc: opensource.kernel@...o.com
Subject: [PATCH 2/2] mm: multi-gen lru: fix stat count
For multi-gen lru reclaim in evict_folios, like shrink_inactive_list,
gather folios which isolate to reclaim, and invoke shirnk_folio_list.
But, when complete shrink, it not gather shrink reclaim stat into sc,
we can't get info like nr_dirty\congested in reclaim, and then
control writeback, dirty number and mark as LRUVEC_CONGESTED, or
just bpf trace shrink and get correct sc stat.
This patch fix this by simple copy code from shrink_inactive_list when
end of shrink list.
Signed-off-by: Huan Yang <link@...o.com>
---
mm/vmscan.c | 35 +++++++++++++++++++++++++++++++++++
1 file changed, 35 insertions(+)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 21099b9f21e0..88d1d586aea5 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -4593,6 +4593,41 @@ static int evict_folios(struct lruvec *lruvec, struct scan_control *sc, int swap
*/
nr_taken = sc->nr_scanned - nr_taken;
+ /*
+ * If dirty folios 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 folios 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 folios 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.
+ */
+ if (unlikely(stat.nr_unqueued_dirty == nr_taken)) {
+ wakeup_flusher_threads(WB_REASON_VMSCAN);
+ /*
+ * For cgroupv1 dirty throttling is achieved by waking up
+ * the kernel flusher here and later waiting on folios
+ * which are in writeback to finish (see shrink_folio_list()).
+ *
+ * Flusher may not be able to issue writeback quickly
+ * enough for cgroupv1 writeback throttling to work
+ * on a large system.
+ */
+ if (!writeback_throttling_sane(sc))
+ reclaim_throttle(pgdat, VMSCAN_THROTTLE_WRITEBACK);
+ }
+
+ sc->nr.dirty += stat.nr_dirty;
+ sc->nr.congested += stat.nr_congested;
+ sc->nr.unqueued_dirty += stat.nr_unqueued_dirty;
+ sc->nr.writeback += stat.nr_writeback;
+ sc->nr.immediate += stat.nr_immediate;
+ sc->nr.taken += nr_taken;
+ if (type)
+ sc->nr.file_taken += nr_taken;
+
sc->nr_reclaimed += total_reclaimed;
trace_mm_vmscan_lru_shrink_inactive(pgdat->node_id, nr_taken,
total_reclaimed, &stat,
--
2.34.1
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