linux-kernel - Re: [PATCH 08/10] mm/page_alloc: use get_onbuddy

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Message-ID: <53BB42E3.4060005@lge.com>
Date:	Tue, 08 Jul 2014 10:01:23 +0900
From:	Gioh Kim <gioh.kim@....com>
To:	Vlastimil Babka <vbabka@...e.cz>,
	Joonsoo Kim <iamjoonsoo.kim@....com>,
	Andrew Morton <akpm@...ux-foundation.org>
CC:	"Kirill A. Shutemov" <kirill.shutemov@...ux.intel.com>,
	Rik van Riel <riel@...hat.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Mel Gorman <mgorman@...e.de>,
	Johannes Weiner <hannes@...xchg.org>,
	Minchan Kim <minchan@...nel.org>,
	Yasuaki Ishimatsu <isimatu.yasuaki@...fujitsu.com>,
	Zhang Yanfei <zhangyanfei@...fujitsu.com>,
	"Srivatsa S. Bhat" <srivatsa.bhat@...ux.vnet.ibm.com>,
	Tang Chen <tangchen@...fujitsu.com>,
	Naoya Horiguchi <n-horiguchi@...jp.nec.com>,
	Bartlomiej Zolnierkiewicz <b.zolnierkie@...sung.com>,
	Wen Congyang <wency@...fujitsu.com>,
	Marek Szyprowski <m.szyprowski@...sung.com>,
	Michal Nazarewicz <mina86@...a86.com>,
	Laura Abbott <lauraa@...eaurora.org>,
	Heesub Shin <heesub.shin@...sung.com>,
	"Aneesh Kumar K.V" <aneesh.kumar@...ux.vnet.ibm.com>,
	Ritesh Harjani <ritesh.list@...il.com>,
	t.stanislaws@...sung.com, linux-mm@...ck.org,
	linux-kernel@...r.kernel.org
Subject: Re: [PATCH 08/10] mm/page_alloc: use get_onbuddy_migratetype() to
 get buddy list type



2014-07-08 오전 12:57, Vlastimil Babka 쓴 글:
> On 07/04/2014 09:57 AM, Joonsoo Kim wrote:
>> When isolating free page, what we want to know is which list
>> the page is linked. If it is linked in isolate migratetype buddy list,
>> we can skip watermark check and freepage counting. And if it is linked
>> in CMA migratetype buddy list, we need to fixup freepage counting. For
>> this purpose, get_onbuddy_migratetype() is more fit and cheap than
>> get_pageblock_migratetype(). So use it.
>
> Hm but you made get_onbuddy_migratetype() work only with CONFIG_MEMORY_ISOLATION. And __isolate_free_page is (despite the name) not at all limited to CONFIG_MEMORY_ISOLATION.
>

Current __isolate_free_page is called by only split_free_page, and split_free_page by isolate_freepages_block.
split_free_page is called only for isolated pages now but It can be changed someday.
I think get_onbuddy_migratetype should work with any situation.

And I think the name of get_onbuddy_migratetype is confused.
Because of _onbuddy_, it might look like that the pages are buddy pages.
I think the original name _freepage_ is proper one.


>> Signed-off-by: Joonsoo Kim <iamjoonsoo.kim@....com>
>> ---
>>   mm/page_alloc.c |    2 +-
>>   1 file changed, 1 insertion(+), 1 deletion(-)
>>
>> diff --git a/mm/page_alloc.c b/mm/page_alloc.c
>> index e1c4c3e..d9fb8bb 100644
>> --- a/mm/page_alloc.c
>> +++ b/mm/page_alloc.c
>> @@ -1597,7 +1597,7 @@ static int __isolate_free_page(struct page *page, unsigned int order)
>>       BUG_ON(!PageBuddy(page));
>>
>>       zone = page_zone(page);
>> -    mt = get_pageblock_migratetype(page);
>> +    mt = get_onbuddy_migratetype(page);
>>
>>       if (!is_migrate_isolate(mt)) {
>>           /* Obey watermarks as if the page was being allocated */
>>
>
>
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