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From: Xishi Qiu <qiuxishi@huawei.com>
To: "mel@csn.ul.ie" <mel@csn.ul.ie>, Vlastimil Babka <vbabka@suse.cz>,
	David Rientjes <rientjes@google.com>,
	Joonsoo Kim <js1304@gmail.com>,
	Mel Gorman <mgorman@techsingularity.net>
Cc: Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>
Subject: mm/compact: why use low watermark to determine whether compact is finished instead of use high watermark?
Date: Fri, 22 Jul 2016 16:56:52 +0800	[thread overview]
Message-ID: <5791DFD4.5080207@huawei.com> (raw)

Hi,

I find all the watermarks in mm/compaction.c are low_wmark_pages(),
so why not use high watermark to determine whether compact is finished?

e.g. 
__alloc_pages_nodemask()
	get_page_from_freelist()
	this is fast path, use use low_wmark_pages() in __zone_watermark_ok()

	__alloc_pages_slowpath()
	this is slow path, usually use min_wmark_pages()

kswapd
	balance_pgdat()
	use high_wmark_pages() to determine whether zone is balanced

Thanks,
Xishi Qiu

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             reply	other threads:[~2016-07-22  8:57 UTC|newest]

Thread overview: 4+ messages / expand[flat|nested]  mbox.gz  Atom feed  top
2016-07-22  8:56 Xishi Qiu [this message]
2016-07-22  9:04 ` Vlastimil Babka
2016-07-22  9:21   ` Xishi Qiu
2016-07-22  9:30     ` Vlastimil Babka

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