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From: Minchan Kim <minchan@kernel.org>
To: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: "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>, Shaohua Li <shli@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: Mon, 19 Sep 2016 16:11:53 +0900	[thread overview]
Message-ID: <20160919071153.GB4083@bbox> (raw)
In-Reply-To: <045D8A5597B93E4EBEDDCBF1FC15F50935BF9343@fmsmsx104.amr.corp.intel.com>

Hi Tim,

On Tue, Sep 13, 2016 at 11:52:27PM +0000, Chen, Tim C wrote:
> >>
> >> - Avoid CPU time for splitting, collapsing THP across swap out/in.
> >
> >Yes, if you want, please give us how bad it is.
> >
> 
> It could be pretty bad.  In an experiment with THP turned on and we
> enter swap, 50% of the cpu are spent in the page compaction path.  

It's page compaction overhead, especially, pageblock_pfn_to_page.
Why is it related to overhead THP split for swapout?
I don't understand.

> So if we could deal with units of large page for swap, the splitting
> and compaction of ordinary pages to large page overhead could be avoided.
> 
>    51.89%    51.89%            :1688  [kernel.kallsyms]   [k] pageblock_pfn_to_page                       
>                       |
>                       --- pageblock_pfn_to_page
>                          |          
>                          |--64.57%-- compaction_alloc
>                          |          migrate_pages
>                          |          compact_zone
>                          |          compact_zone_order
>                          |          try_to_compact_pages
>                          |          __alloc_pages_direct_compact
>                          |          __alloc_pages_nodemask
>                          |          alloc_pages_vma
>                          |          do_huge_pmd_anonymous_page
>                          |          handle_mm_fault
>                          |          __do_page_fault
>                          |          do_page_fault
>                          |          page_fault
>                          |          0x401d9a
>                          |          
>                          |--34.62%-- compact_zone
>                          |          compact_zone_order
>                          |          try_to_compact_pages
>                          |          __alloc_pages_direct_compact
>                          |          __alloc_pages_nodemask
>                          |          alloc_pages_vma
>                          |          do_huge_pmd_anonymous_page
>                          |          handle_mm_fault
>                          |          __do_page_fault
>                          |          do_page_fault
>                          |          page_fault
>                          |          0x401d9a
>                           --0.81%-- [...]
> 
> Tim

WARNING: multiple messages have this Message-ID (diff)
From: Minchan Kim <minchan@kernel.org>
To: "Chen, Tim C" <tim.c.chen@intel.com>
Cc: "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>, Shaohua Li <shli@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: Mon, 19 Sep 2016 16:11:53 +0900	[thread overview]
Message-ID: <20160919071153.GB4083@bbox> (raw)
In-Reply-To: <045D8A5597B93E4EBEDDCBF1FC15F50935BF9343@fmsmsx104.amr.corp.intel.com>

Hi Tim,

On Tue, Sep 13, 2016 at 11:52:27PM +0000, Chen, Tim C wrote:
> >>
> >> - Avoid CPU time for splitting, collapsing THP across swap out/in.
> >
> >Yes, if you want, please give us how bad it is.
> >
> 
> It could be pretty bad.  In an experiment with THP turned on and we
> enter swap, 50% of the cpu are spent in the page compaction path.  

It's page compaction overhead, especially, pageblock_pfn_to_page.
Why is it related to overhead THP split for swapout?
I don't understand.

> So if we could deal with units of large page for swap, the splitting
> and compaction of ordinary pages to large page overhead could be avoided.
> 
>    51.89%    51.89%            :1688  [kernel.kallsyms]   [k] pageblock_pfn_to_page                       
>                       |
>                       --- pageblock_pfn_to_page
>                          |          
>                          |--64.57%-- compaction_alloc
>                          |          migrate_pages
>                          |          compact_zone
>                          |          compact_zone_order
>                          |          try_to_compact_pages
>                          |          __alloc_pages_direct_compact
>                          |          __alloc_pages_nodemask
>                          |          alloc_pages_vma
>                          |          do_huge_pmd_anonymous_page
>                          |          handle_mm_fault
>                          |          __do_page_fault
>                          |          do_page_fault
>                          |          page_fault
>                          |          0x401d9a
>                          |          
>                          |--34.62%-- compact_zone
>                          |          compact_zone_order
>                          |          try_to_compact_pages
>                          |          __alloc_pages_direct_compact
>                          |          __alloc_pages_nodemask
>                          |          alloc_pages_vma
>                          |          do_huge_pmd_anonymous_page
>                          |          handle_mm_fault
>                          |          __do_page_fault
>                          |          do_page_fault
>                          |          page_fault
>                          |          0x401d9a
>                           --0.81%-- [...]
> 
> Tim

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  reply	other threads:[~2016-09-19  7:11 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 [this message]
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
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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