From: "Huang\, Ying" <ying.huang@intel.com>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "Huang, Ying" <ying.huang@intel.com>,
tim.c.chen@intel.com, dave.hansen@intel.com,
andi.kleen@intel.com, aaron.lu@intel.com, linux-mm@kvack.org,
linux-kernel@vger.kernel.org, Hugh Dickins <hughd@google.com>,
Shaohua Li <shli@kernel.org>, Minchan Kim <minchan@kernel.org>,
Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH -v2 01/10] swap: Change SWAPFILE_CLUSTER to 512
Date: Fri, 02 Sep 2016 13:37:29 -0700 [thread overview]
Message-ID: <87a8fqca2e.fsf@yhuang-mobile.sh.intel.com> (raw)
In-Reply-To: <20160902133016.0a150c880174fa97f161912f@linux-foundation.org> (Andrew Morton's message of "Fri, 2 Sep 2016 13:30:16 -0700")
Andrew Morton <akpm@linux-foundation.org> writes:
> On Thu, 01 Sep 2016 16:04:57 -0700 "Huang\, Ying" <ying.huang@intel.com> wrote:
>
>> >> }
>> >>
>> >> -#define SWAPFILE_CLUSTER 256
>> >> +#define SWAPFILE_CLUSTER 512
>> >> #define LATENCY_LIMIT 256
>> >>
>> >
>> > What happens to architectures which have different HPAGE_SIZE and/or
>> > PAGE_SIZE?
>>
>> For the architecture with HPAGE_SIZE / PAGE_SIZE == 512 (for example
>> x86_64), the huge page swap optimizing will be turned on. For other
>> architectures, it will be turned off as before.
>>
>> This mostly because I don't know whether it is a good idea to turn on
>> THP swap optimizing for the architectures other than x86_64. For
>> example, it appears that the huge page size is 8M (1<<23) on SPARC. But
>> I don't know whether 8M is too big for a swap cluster. And it appears
>> that the huge page size could be as large as 512M on MIPS.
>
> This doesn't sounds very organized. If some architecture with some
> config happens to have HPAGE_SIZE / PAGE_SIZE == 512 then the feature
> will be turned on; otherwise it will be turned off. Nobody will even
> notice that it happened.
>
> Would it not be better to do
>
> #ifdef CONFIG_SOMETHING
> #define SWAPFILE_CLUSTER (HPAGE_SIZE / PAGE_SIZE)
> #else
> #define SWAPFILE_CLUSTER 256
> #endif
>
> and, by using CONFIG_SOMETHING in the other appropriate places, enable
> the feature in the usual fashion?
Yes. That is better. I will change it in the next version.
Best Regards,
Huang, Ying
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next prev parent reply other threads:[~2016-09-02 20:37 UTC|newest]
Thread overview: 15+ messages / expand[flat|nested] mbox.gz Atom feed top
2016-09-01 15:16 [PATCH -v2 00/10] THP swap: Delay splitting THP during swapping out Huang, Ying
2016-09-01 15:16 ` [PATCH -v2 01/10] swap: Change SWAPFILE_CLUSTER to 512 Huang, Ying
2016-09-01 21:22 ` Andrew Morton
2016-09-01 23:04 ` Huang, Ying
2016-09-02 20:30 ` Andrew Morton
2016-09-02 20:37 ` Huang, Ying [this message]
2016-09-01 15:16 ` [PATCH -v2 02/10] mm, memcg: Add swap_cgroup_iter iterator Huang, Ying
2016-09-01 15:16 ` [PATCH -v2 03/10] mm, memcg: Support to charge/uncharge multiple swap entries Huang, Ying
2016-09-01 15:16 ` [PATCH -v2 04/10] mm, THP, swap: Add swap cluster allocate/free functions Huang, Ying
2016-09-01 15:16 ` [PATCH -v2 05/10] mm, THP, swap: Add get_huge_swap_page() Huang, Ying
2016-09-01 15:16 ` [PATCH -v2 06/10] mm, THP, swap: Support to clear SWAP_HAS_CACHE for huge page Huang, Ying
2016-09-01 15:17 ` [PATCH -v2 07/10] mm, THP, swap: Support to add/delete THP to/from swap cache Huang, Ying
2016-09-01 15:17 ` [PATCH -v2 08/10] mm, THP: Add can_split_huge_page() Huang, Ying
2016-09-01 15:17 ` [PATCH -v2 09/10] mm, THP, swap: Support to split THP in swap cache Huang, Ying
2016-09-01 15:17 ` [PATCH -v2 10/10] mm, THP, swap: Delay splitting THP during swap out Huang, Ying
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