[patch 155/262] mm/vmscan: increase the timeout if page reclaim is not making progress

Andrew Morton
2021-11-05T20:43:02Z

From: Mel Gorman <mgorman@techsingularity.net>
Subject: mm/vmscan: increase the timeout if page reclaim is not making progress

Tracing of the stutterp workload showed the following delays

1 usect_delayed=124000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=128000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=176000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=536000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=544000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=556000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=624000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=716000 reason=VMSCAN_THROTTLE_NOPROGRESS
1 usect_delayed=772000 reason=VMSCAN_THROTTLE_NOPROGRESS
2 usect_delayed=512000 reason=VMSCAN_THROTTLE_NOPROGRESS
16 usect_delayed=120000 reason=VMSCAN_THROTTLE_NOPROGRESS
53 usect_delayed=116000 reason=VMSCAN_THROTTLE_NOPROGRESS
116 usect_delayed=112000 reason=VMSCAN_THROTTLE_NOPROGRESS
5907 usect_delayed=108000 reason=VMSCAN_THROTTLE_NOPROGRESS
71741 usect_delayed=104000 reason=VMSCAN_THROTTLE_NOPROGRESS

All the throttling hit the full timeout and then there was wakeup delays
meaning that the wakeups are premature as no other reclaimer such as
kswapd has made progress. This patch increases the maximum timeout.

Link: https://lkml.kernel.org/r/20211022144651.19914-8-mgorman@techsingularity.net
Signed-off-by: Mel Gorman <mgorman@techsingularity.net>
Acked-by: Vlastimil Babka <vbabka@suse.cz>
Cc: Andreas Dilger <adilger.kernel@dilger.ca>
Cc: "Darrick J . Wong" <djwong@kernel.org>
Cc: Dave Chinner <david@fromorbit.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Jonathan Corbet <corbet@lwn.net>
Cc: Matthew Wilcox <willy@infradead.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: NeilBrown <neilb@suse.de>
Cc: Rik van Riel <riel@surriel.com>
Cc: "Theodore Ts'o" <tytso@mit.edu>
Signed-off-by: Andrew Morton <akpm@linux-foundation.org>
---

mm/vmscan.c | 2 +-
1 file changed, 1 insertion(+), 1 deletion(-)

--- a/mm/vmscan.c~mm-vmscan-increase-the-timeout-if-page-reclaim-is-not-making-progress
+++ a/mm/vmscan.c
@@ -1042,7 +1042,7 @@ void reclaim_throttle(pg_data_t *pgdat,

break;
case VMSCAN_THROTTLE_NOPROGRESS:
- timeout = HZ/10;
+ timeout = HZ/2;
break;
case VMSCAN_THROTTLE_ISOLATED:
timeout = HZ/50;
_