From: Johannes Weiner <hannes@cmpxchg.org>
To: "Huang, Ying" <ying.huang@intel.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
"Kirill A. Shutemov" <kirill@shutemov.name>,
linux-mm@kvack.org, linux-kernel@vger.kernel.org
Subject: Re: [PATCH -mm -v10 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map
Date: Tue, 25 Apr 2017 17:46:18 -0400 [thread overview]
Message-ID: <20170425214618.GB6841@cmpxchg.org> (raw)
In-Reply-To: <20170425125658.28684-4-ying.huang@intel.com>
On Tue, Apr 25, 2017 at 08:56:58PM +0800, Huang, Ying wrote:
> From: Huang Ying <ying.huang@intel.com>
>
> If there is no compound map for a THP (Transparent Huge Page), it is
> possible that the map count of some sub-pages of the THP is 0. So it
> is better to split the THP before swapping out. In this way, the
> sub-pages not mapped will be freed, and we can avoid the unnecessary
> swap out operations for these sub-pages.
>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Signed-off-by: "Huang, Ying" <ying.huang@intel.com>
Acked-by: Johannes Weiner <hannes@cmpxchg.org>
CC Kirill to double check the reasoning here
> ---
> mm/swap_state.c | 16 +++++++++++++---
> 1 file changed, 13 insertions(+), 3 deletions(-)
>
> diff --git a/mm/swap_state.c b/mm/swap_state.c
> index 006d91d8fc53..13f83c6bb1b4 100644
> --- a/mm/swap_state.c
> +++ b/mm/swap_state.c
> @@ -192,9 +192,19 @@ int add_to_swap(struct page *page, struct list_head *list)
> VM_BUG_ON_PAGE(!PageLocked(page), page);
> VM_BUG_ON_PAGE(!PageUptodate(page), page);
>
> - /* cannot split, skip it */
> - if (PageTransHuge(page) && !can_split_huge_page(page, NULL))
> - return 0;
> + if (PageTransHuge(page)) {
> + /* cannot split, skip it */
> + if (!can_split_huge_page(page, NULL))
> + return 0;
> + /*
> + * Split pages without a PMD map right away. Chances
> + * are some or all of the tail pages can be freed
> + * without IO.
> + */
> + if (!compound_mapcount(page) &&
> + split_huge_page_to_list(page, list))
> + return 0;
> + }
>
> retry:
> entry = get_swap_page(page);
> --
> 2.11.0
next prev parent reply other threads:[~2017-04-25 21:46 UTC|newest]
Thread overview: 26+ messages / expand[flat|nested] mbox.gz Atom feed top
2017-04-25 12:56 [PATCH -mm -v10 0/3] THP swap: Delay splitting THP during swapping out Huang, Ying
2017-04-25 12:56 ` [PATCH -mm -v10 1/3] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
2017-04-27 5:31 ` Minchan Kim
2017-04-27 7:12 ` Huang, Ying
2017-04-27 13:37 ` Johannes Weiner
2017-04-28 8:40 ` Minchan Kim
2017-04-28 12:21 ` Huang, Ying
2017-05-10 1:03 ` Minchan Kim
2017-05-01 10:44 ` Johannes Weiner
2017-05-01 23:53 ` Minchan Kim
2017-05-10 13:56 ` Johannes Weiner
2017-05-10 23:25 ` Minchan Kim
2017-05-11 0:50 ` Huang, Ying
2017-05-11 4:31 ` Minchan Kim
2017-05-12 2:21 ` [PATCH 1/2] mm: swap: unify swap slot free functions to put_swap_page Minchan Kim
2017-05-12 2:21 ` [PATCH 2/2] mm: swap: move anonymous THP split logic to vmscan Minchan Kim
2017-05-12 16:48 ` Johannes Weiner
2017-05-12 16:47 ` [PATCH 1/2] mm: swap: unify swap slot free functions to put_swap_page Johannes Weiner
2017-05-11 1:22 ` [PATCH -mm -v10 1/3] mm, THP, swap: Delay splitting THP during swap out Minchan Kim
2017-05-11 10:40 ` Johannes Weiner
2017-05-12 1:34 ` Minchan Kim
2017-04-25 12:56 ` [PATCH -mm -v10 2/3] mm, THP, swap: Check whether THP can be split firstly Huang, Ying
2017-04-25 21:43 ` Johannes Weiner
2017-04-25 12:56 ` [PATCH -mm -v10 3/3] mm, THP, swap: Enable THP swap optimization only if has compound map Huang, Ying
2017-04-25 21:46 ` Johannes Weiner [this message]
2017-04-28 13:16 ` Kirill A. Shutemov
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