From 3d9c3fe7414202099b6deecdd62cc9da80c56394 Mon Sep 17 00:00:00 2001
From: Mel Gorman <mgorman@techsingularity.net>
Date: Fri, 5 Nov 2021 13:42:49 -0700
Subject: [PATCH] mm/vmscan: delay waking of tasks throttled on NOPROGRESS
References: bsc#1190208 (MM functional and performance backports)
Patch-mainline: v5.16-rc1
Git-commit: 66ce520bb7c22848bfdf3180d7e760a066dbcfbe
Tracing indicates that tasks throttled on NOPROGRESS are woken
prematurely resulting in occasional massive spikes in direct reclaim
activity. This patch wakes tasks throttled on NOPROGRESS if reclaim
efficiency is at least 12%.
Link: https://lkml.kernel.org/r/20211022144651.19914-9-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>
Signed-off-by: Linus Torvalds <torvalds@linux-foundation.org>
Signed-off-by: Mel Gorman <mgorman@suse.de>
---
mm/vmscan.c | 7 +++++--
1 file changed, 5 insertions(+), 2 deletions(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index 9e554e54af4f..d79357587027 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -3205,8 +3205,11 @@ static inline bool compaction_ready(struct zone *zone, struct scan_control *sc)
static void consider_reclaim_throttle(pg_data_t *pgdat, struct scan_control *sc)
{
- /* If reclaim is making progress, wake any throttled tasks. */
- if (sc->nr_reclaimed) {
+ /*
+ * If reclaim is making progress greater than 12% efficiency then
+ * wake all the NOPROGRESS throttled tasks.
+ */
+ if (sc->nr_reclaimed > (sc->nr_scanned >> 3)) {
wait_queue_head_t *wqh;
wqh = &pgdat->reclaim_wait[VMSCAN_THROTTLE_NOPROGRESS];