From: Yang Shi <yang.shi@linux.alibaba.com>
To: ying.huang@intel.com, hannes@cmpxchg.org, mhocko@suse.com,
mgorman@techsingularity.net, kirill.shutemov@linux.intel.com,
hughd@google.com, shakeelb@google.com,
william.kucharski@oracle.com, akpm@linux-foundation.org
Cc: yang.shi@linux.alibaba.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org
Subject: [v2 PATCH] mm: vmscan: correct nr_reclaimed for THP
Date: Sat, 11 May 2019 00:23:40 +0800 [thread overview]
Message-ID: <1557505420-21809-1-git-send-email-yang.shi@linux.alibaba.com> (raw)
Since commit bd4c82c22c36 ("mm, THP, swap: delay splitting THP after
swapped out"), THP can be swapped out in a whole. But, nr_reclaimed
still gets inc'ed by one even though a whole THP (512 pages) gets
swapped out.
This doesn't make too much sense to memory reclaim. For example, direct
reclaim may just need reclaim SWAP_CLUSTER_MAX pages, reclaiming one THP
could fulfill it. But, if nr_reclaimed is not increased correctly,
direct reclaim may just waste time to reclaim more pages,
SWAP_CLUSTER_MAX * 512 pages in worst case.
This change may result in more reclaimed pages than scanned pages showed
by /proc/vmstat since scanning one head page would reclaim 512 base pages.
Cc: "Huang, Ying" <ying.huang@intel.com>
Cc: Johannes Weiner <hannes@cmpxchg.org>
Cc: Michal Hocko <mhocko@suse.com>
Cc: Mel Gorman <mgorman@suse.de>
Cc: "Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>
Cc: Hugh Dickins <hughd@google.com>
Reviewed-by: Shakeel Butt <shakeelb@google.com>
Signed-off-by: Yang Shi <yang.shi@linux.alibaba.com>
---
v2: Added Shakeel's Reviewed-by
Use hpage_nr_pages instead of compound_order per Huang Ying and William Kucharski
mm/vmscan.c | 6 +++++-
1 file changed, 5 insertions(+), 1 deletion(-)
diff --git a/mm/vmscan.c b/mm/vmscan.c
index fd9de50..4226d6b 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -1446,7 +1446,11 @@ static unsigned long shrink_page_list(struct list_head *page_list,
unlock_page(page);
free_it:
- nr_reclaimed++;
+ /*
+ * THP may get swapped out in a whole, need account
+ * all base pages.
+ */
+ nr_reclaimed += hpage_nr_pages(page);
/*
* Is there need to periodically free_page_list? It would
--
1.8.3.1
next reply other threads:[~2019-05-10 16:24 UTC|newest]
Thread overview: 10+ messages / expand[flat|nested] mbox.gz Atom feed top
2019-05-10 16:23 Yang Shi [this message]
2019-05-13 8:09 ` [v2 PATCH] mm: vmscan: correct nr_reclaimed for THP Michal Hocko
[not found] ` <c3c26c7a-748c-6090-67f4-3014bedea2e6@linux.alibaba.com>
2019-05-13 21:45 ` Michal Hocko
2019-05-14 4:36 ` Yang Shi
2019-05-14 6:20 ` Michal Hocko
2019-05-14 20:44 ` Yang Shi
2019-05-16 15:10 ` Johannes Weiner
2019-05-20 9:43 ` Yang Shi
2019-05-21 3:16 ` Yang Shi
2019-05-21 6:54 ` Yang Shi
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