Date: Thu, 15 Aug 2013 14:42:09 +0100
From: Mel Gorman <mgorman@suse.de>
To: Minchan Kim <minchan@kernel.org>
Cc: Xishi Qiu <qiuxishi@huawei.com>, Andrew Morton <akpm@linux-foundation.org>,
        riel@redhat.com, aquini@redhat.com, linux-mm@kvack.org,
        LKML <linux-kernel@vger.kernel.org>
Subject: Re: [PATCH] mm: skip the page buddy block instead of one page
Message-ID: <20130815134209.GW2296@suse.de>
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On Thu, Aug 15, 2013 at 10:19:35PM +0900, Minchan Kim wrote:
> > 
> > Why? We're looking for pages to migrate. If the page is free and at the
> > maximum order then there is no point searching in the middle of a free
> > page.
> 
> isolate_migratepages_range API works with [low_pfn, end_pfn)
> and we can't guarantee page_order in normal compaction path
> so I'd like to limit the skipping by end_pfn conservatively.
> 

Fine

s/MAX_ORDER_NR_PAGES/pageblock_nr_pages/

and take the min of it and

low_pfn = min(low_pfn, end_pfn - 1)

-- 
Mel Gorman
SUSE Labs
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