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Date: Wed, 21 Mar 2018 15:42:49 +0800
From: Aaron Lu <aaron.lu@intel.com>
Subject: Re: [RFC PATCH v2 2/4] mm/__free_one_page: skip merge for order-0
 page unless compaction failed
Message-ID: <20180321074249.GA1855@aaronlu>
References: <20180320085452.24641-1-aaron.lu@intel.com>
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To: "Figo.zhang" <figo1802@gmail.com>
Cc: Linux MM <linux-mm@kvack.org>, LKML <linux-kernel@vger.kernel.org>, Andrew Morton <akpm@linux-foundation.org>, Huang Ying <ying.huang@intel.com>, Dave Hansen <dave.hansen@linux.intel.com>, Kemi Wang <kemi.wang@intel.com>, Tim Chen <tim.c.chen@linux.intel.com>, Andi Kleen <ak@linux.intel.com>, Michal Hocko <mhocko@suse.com>, Vlastimil Babka <vbabka@suse.cz>, Mel Gorman <mgorman@techsingularity.net>, Matthew Wilcox <willy@infradead.org>, Daniel Jordan <daniel.m.jordan@oracle.com>

On Tue, Mar 20, 2018 at 10:59:16PM -0700, Figo.zhang wrote:
> 2018-03-20 21:53 GMT-07:00 Aaron Lu <aaron.lu@intel.com>:
> 
> > On Tue, Mar 20, 2018 at 09:21:33PM -0700, Figo.zhang wrote:
> > > suppose that in free_one_page() will try to merge to high order anytime ,
> > > but now in your patch,
> > > those merge has postponed when system in low memory status, it is very
> > easy
> > > let system trigger
> > > low memory state and get poor performance.
> >
> > Merge or not merge, the size of free memory is not affected.
> >
> 
> yes, the total free memory is not impact, but will influence the higher
> order allocation.

Yes, that's correct.