[RFC PATCH 2/4] mm/swap.c: bail out early for no memcg and no numa

Alex Shi
2020-12-25T10:02:57Z

If a system has memcg disabled and no numa node, like a embedded system,
there is no needs to do the pagevec sort, since only just one lruvec in
system. In this situation, we could skip the pagevec sorting.

Signed-off-by: Alex Shi <alex.shi@linux.alibaba.com>
Cc: Konstantin Khlebnikov <koct9i@gmail.com>
Cc: Hugh Dickins <hughd@google.com>
Cc: Yu Zhao <yuzhao@google.com>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Matthew Wilcox (Oracle) <willy@infradead.org>
Cc: Andrew Morton <akpm@linux-foundation.org>
Cc: linux-mm@kvack.org
Cc: linux-kernel@vger.kernel.org
---
mm/swap.c | 19 ++++++++++---------
1 file changed, 10 insertions(+), 9 deletions(-)

diff --git a/mm/swap.c b/mm/swap.c
index 994641331bf7..bb5300b7e321 100644
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -235,6 +235,7 @@ void sort_isopv(struct pagevec *pvec, struct pagevec *isopv,

pagevec_init(&busypv);

+
for (i = 0, j = 0; i < pagevec_count(pvec); i++) {
struct page *page = pvec->pages[i];

@@ -253,7 +254,8 @@ void sort_isopv(struct pagevec *pvec, struct pagevec *isopv,
if (pagevec_count(&busypv))
release_pages(busypv.pages, busypv.nr);

- shell_sort(isopv, lvaddr);
+ if (!mem_cgroup_disabled() || num_online_nodes() > 1)
+ shell_sort(isopv, lvaddr);
}

static void pagevec_lru_move_fn(struct pagevec *pvec,
@@ -263,13 +265,12 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
struct lruvec *lruvec = NULL;
unsigned long flags = 0;
unsigned long lvaddr[PAGEVEC_SIZE];
- struct pagevec isopv;
-
- pagevec_init(&isopv);
+ struct pagevec sortedpv;

- sort_isopv(pvec, &isopv, lvaddr);
+ pagevec_init(&sortedpv);
+ sort_isopv(pvec, &sortedpv, lvaddr);

- n = pagevec_count(&isopv);
+ n = pagevec_count(&sortedpv);
if (!n)
return;

@@ -284,12 +285,12 @@ static void pagevec_lru_move_fn(struct pagevec *pvec,
spin_lock_irqsave(&lruvec->lru_lock, flags);
}

- (*move_fn)(isopv.pages[i], lruvec);
+ (*move_fn)(sortedpv.pages[i], lruvec);

- SetPageLRU(isopv.pages[i]);
+ SetPageLRU(sortedpv.pages[i]);
}
spin_unlock_irqrestore(&lruvec->lru_lock, flags);
- release_pages(isopv.pages, isopv.nr);
+ release_pages(sortedpv.pages, sortedpv.nr);
}

static void pagevec_move_tail_fn(struct page *page, struct lruvec *lruvec)
--
2.29.GIT