From: Andi Kleen <andi@firstfloor.org>
To: "Chen\, Tim C" <tim.c.chen@intel.com>
Cc: Shaohua Li <shli@kernel.org>, "Huang\,
Ying" <ying.huang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>, "Hansen\,
Dave" <dave.hansen@intel.com>, "Kleen\,
Andi" <andi.kleen@intel.com>, "Lu\, Aaron" <aaron.lu@intel.com>,
"linux-mm\@kvack.org" <linux-mm@kvack.org>,
"linux-kernel\@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Hugh Dickins <hughd@google.com>, Minchan Kim <minchan@kernel.org>,
Rik van Riel <riel@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Vladimir Davydov <vdavydov@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out
Date: Thu, 22 Sep 2016 16:53:02 -0700 [thread overview]
Message-ID: <87y42jo5k1.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <045D8A5597B93E4EBEDDCBF1FC15F50935C1AD83@fmsmsx104.amr.corp.intel.com> (Tim C. Chen's message of "Thu, 22 Sep 2016 23:49:00 +0000")
"Chen, Tim C" <tim.c.chen@intel.com> writes:
>>
>>So this is impossible without THP swapin. While 2M swapout makes a lot of
>>sense, I doubt 2M swapin is really useful. What kind of application is 'optimized'
>>to do sequential memory access?
Anything that touches regions larger than 4K and we want to do the
kernel do minimal work to manage the swapping.
>
> We waste a lot of cpu cycles to re-compact 4K pages back to a large page
> under THP. Swapping it back in as a single large page can avoid
> fragmentation and this overhead.
Also splitting something just to merge it again is wasteful.
A lot of big improvements in the block and VM and network layers
over the years came from avoiding that kind of wasteful work.
-Andi
WARNING: multiple messages have this Message-ID (diff)
From: Andi Kleen <andi@firstfloor.org>
To: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: Shaohua Li <shli@kernel.org>,
"Huang, Ying" <ying.huang@intel.com>,
Andrew Morton <akpm@linux-foundation.org>,
"Hansen, Dave" <dave.hansen@intel.com>,
"Kleen, Andi" <andi.kleen@intel.com>,
"Lu, Aaron" <aaron.lu@intel.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
Hugh Dickins <hughd@google.com>, Minchan Kim <minchan@kernel.org>,
Rik van Riel <riel@redhat.com>,
Andrea Arcangeli <aarcange@redhat.com>,
"Kirill A . Shutemov" <kirill.shutemov@linux.intel.com>,
Vladimir Davydov <vdavydov@virtuozzo.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Michal Hocko <mhocko@kernel.org>
Subject: Re: [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out
Date: Thu, 22 Sep 2016 16:53:02 -0700 [thread overview]
Message-ID: <87y42jo5k1.fsf@tassilo.jf.intel.com> (raw)
In-Reply-To: <045D8A5597B93E4EBEDDCBF1FC15F50935C1AD83@fmsmsx104.amr.corp.intel.com> (Tim C. Chen's message of "Thu, 22 Sep 2016 23:49:00 +0000")
"Chen, Tim C" <tim.c.chen@intel.com> writes:
>>
>>So this is impossible without THP swapin. While 2M swapout makes a lot of
>>sense, I doubt 2M swapin is really useful. What kind of application is 'optimized'
>>to do sequential memory access?
Anything that touches regions larger than 4K and we want to do the
kernel do minimal work to manage the swapping.
>
> We waste a lot of cpu cycles to re-compact 4K pages back to a large page
> under THP. Swapping it back in as a single large page can avoid
> fragmentation and this overhead.
Also splitting something just to merge it again is wasteful.
A lot of big improvements in the block and VM and network layers
over the years came from avoiding that kind of wasteful work.
-Andi
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next prev parent reply other threads:[~2016-09-22 23:53 UTC|newest]
Thread overview: 120+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-07 16:45 [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Huang, Ying
2016-09-07 16:45 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 01/10] mm, swap: Make swap cluster size same of THP size on x86_64 Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-08 5:45 ` Anshuman Khandual
2016-09-08 5:45 ` Anshuman Khandual
2016-09-08 18:07 ` Huang, Ying
2016-09-08 18:07 ` Huang, Ying
2016-09-19 17:09 ` Johannes Weiner
2016-09-19 17:09 ` Johannes Weiner
2016-09-20 2:01 ` Huang, Ying
2016-09-20 2:01 ` Huang, Ying
2016-09-22 19:25 ` Johannes Weiner
2016-09-22 19:25 ` Johannes Weiner
2016-09-23 8:47 ` Huang, Ying
2016-09-08 8:21 ` Anshuman Khandual
2016-09-08 8:21 ` Anshuman Khandual
2016-09-08 11:03 ` Kirill A. Shutemov
2016-09-08 11:03 ` Kirill A. Shutemov
2016-09-08 17:39 ` Huang, Ying
2016-09-08 17:39 ` Huang, Ying
2016-09-08 11:07 ` Kirill A. Shutemov
2016-09-08 11:07 ` Kirill A. Shutemov
2016-09-08 17:23 ` Huang, Ying
2016-09-08 17:23 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 02/10] mm, memcg: Add swap_cgroup_iter iterator Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 03/10] mm, memcg: Support to charge/uncharge multiple swap entries Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-08 5:46 ` Anshuman Khandual
2016-09-08 5:46 ` Anshuman Khandual
2016-09-08 8:28 ` Anshuman Khandual
2016-09-08 8:28 ` Anshuman Khandual
2016-09-08 18:15 ` Huang, Ying
2016-09-08 18:15 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 04/10] mm, THP, swap: Add swap cluster allocate/free functions Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-08 5:49 ` Anshuman Khandual
2016-09-08 5:49 ` Anshuman Khandual
2016-09-08 8:30 ` Anshuman Khandual
2016-09-08 8:30 ` Anshuman Khandual
2016-09-08 18:14 ` Huang, Ying
2016-09-08 18:14 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 05/10] mm, THP, swap: Add get_huge_swap_page() Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-08 11:13 ` Kirill A. Shutemov
2016-09-08 11:13 ` Kirill A. Shutemov
2016-09-08 17:22 ` Huang, Ying
2016-09-08 17:22 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 06/10] mm, THP, swap: Support to clear SWAP_HAS_CACHE for huge page Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 07/10] mm, THP, swap: Support to add/delete THP to/from swap cache Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-08 9:00 ` Anshuman Khandual
2016-09-08 9:00 ` Anshuman Khandual
2016-09-08 18:10 ` Huang, Ying
2016-09-08 18:10 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 08/10] mm, THP: Add can_split_huge_page() Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-08 11:17 ` Kirill A. Shutemov
2016-09-08 11:17 ` Kirill A. Shutemov
2016-09-08 17:02 ` Huang, Ying
2016-09-08 17:02 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 09/10] mm, THP, swap: Support to split THP in swap cache Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-07 16:46 ` [PATCH -v3 10/10] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
2016-09-07 16:46 ` Huang, Ying
2016-09-09 5:43 ` [PATCH -v3 00/10] THP swap: Delay splitting THP during swapping out Minchan Kim
2016-09-09 5:43 ` Minchan Kim
2016-09-09 15:53 ` Tim Chen
2016-09-09 15:53 ` Tim Chen
2016-09-09 20:35 ` Huang, Ying
2016-09-09 20:35 ` Huang, Ying
2016-09-13 6:13 ` Minchan Kim
2016-09-13 6:13 ` Minchan Kim
2016-09-13 6:40 ` Huang, Ying
2016-09-13 6:40 ` Huang, Ying
2016-09-13 7:05 ` Minchan Kim
2016-09-13 7:05 ` Minchan Kim
2016-09-13 8:53 ` Huang, Ying
2016-09-13 8:53 ` Huang, Ying
2016-09-13 9:16 ` Minchan Kim
2016-09-13 9:16 ` Minchan Kim
2016-09-13 23:52 ` Chen, Tim C
2016-09-13 23:52 ` Chen, Tim C
2016-09-19 7:11 ` Minchan Kim
2016-09-19 7:11 ` Minchan Kim
2016-09-19 15:59 ` Tim Chen
2016-09-19 15:59 ` Tim Chen
2016-09-18 1:53 ` Huang, Ying
2016-09-18 1:53 ` Huang, Ying
2016-09-19 7:08 ` Minchan Kim
2016-09-19 7:08 ` Minchan Kim
2016-09-20 2:54 ` Huang, Ying
2016-09-20 2:54 ` Huang, Ying
2016-09-20 5:06 ` Minchan Kim
2016-09-20 5:06 ` Minchan Kim
2016-09-20 5:28 ` Huang, Ying
2016-09-20 5:28 ` Huang, Ying
2016-09-13 14:35 ` Andrea Arcangeli
2016-09-13 14:35 ` Andrea Arcangeli
2016-09-19 17:33 ` Hugh Dickins
2016-09-19 17:33 ` Hugh Dickins
2016-09-22 22:56 ` Shaohua Li
2016-09-22 22:56 ` Shaohua Li
2016-09-22 23:49 ` Chen, Tim C
2016-09-22 23:49 ` Chen, Tim C
2016-09-22 23:53 ` Andi Kleen [this message]
2016-09-22 23:53 ` Andi Kleen
2016-09-23 0:38 ` Rik van Riel
2016-09-23 2:32 ` Huang, Ying
2016-09-23 2:32 ` Huang, Ying
2016-09-25 19:18 ` Shaohua Li
2016-09-25 19:18 ` Shaohua Li
2016-09-26 1:06 ` Minchan Kim
2016-09-26 1:06 ` Minchan Kim
2016-09-26 3:25 ` Huang, Ying
2016-09-26 3:25 ` Huang, Ying
2016-09-23 2:12 ` Huang, Ying
2016-09-23 2:12 ` Huang, Ying
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