linux-kernel - [PATCH v7 1/6] mm/vmscan: make active/inactive ratio as 1:1 for anon lru

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Date:   Thu, 23 Jul 2020 16:49:15 +0900
From:   js1304@...il.com
To:     Andrew Morton <akpm@...ux-foundation.org>
Cc:     linux-mm@...ck.org, linux-kernel@...r.kernel.org,
        Johannes Weiner <hannes@...xchg.org>,
        Michal Hocko <mhocko@...nel.org>,
        Hugh Dickins <hughd@...gle.com>,
        Minchan Kim <minchan@...nel.org>,
        Vlastimil Babka <vbabka@...e.cz>,
        Mel Gorman <mgorman@...hsingularity.net>,
        Matthew Wilcox <willy@...radead.org>, kernel-team@....com,
        Joonsoo Kim <iamjoonsoo.kim@....com>
Subject: [PATCH v7 1/6] mm/vmscan: make active/inactive ratio as 1:1 for anon lru

From: Joonsoo Kim <iamjoonsoo.kim@....com>

Current implementation of LRU management for anonymous page has some
problems. Most important one is that it doesn't protect the workingset,
that is, pages on the active LRU list. Although, this problem will be
fixed in the following patchset, the preparation is required and
this patch does it.

What following patch does is to implement workingset protection. After
the following patchset, newly created or swap-in pages will start their
lifetime on the inactive list. If inactive list is too small, there is not
enough chance to be referenced and the page cannot become the workingset.

In order to provide the newly anonymous or swap-in pages enough chance to
be referenced again, this patch makes active/inactive LRU ratio as 1:1.

This is just a temporary measure. Later patch in the series introduces
workingset detection for anonymous LRU that will be used to better decide
if pages should start on the active and inactive list. Afterwards this
patch is effectively reverted.

Acked-by: Johannes Weiner <hannes@...xchg.org>
Acked-by: Vlastimil Babka <vbabka@...e.cz>
Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
---
 mm/vmscan.c | 2 +-
 1 file changed, 1 insertion(+), 1 deletion(-)

diff --git a/mm/vmscan.c b/mm/vmscan.c
index 6acc956..d5a19c7 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2208,7 +2208,7 @@ static bool inactive_is_low(struct lruvec *lruvec, enum lru_list inactive_lru)
 	active = lruvec_page_state(lruvec, NR_LRU_BASE + active_lru);

 	gb = (inactive + active) >> (30 - PAGE_SHIFT);
-	if (gb)
+	if (gb && is_file_lru(inactive_lru))
 		inactive_ratio = int_sqrt(10 * gb);
 	else
 		inactive_ratio = 1;
-- 
2.7.4