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References: <20090514231555.f52c81eb.minchan.kim@gmail.com>
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Date: Thu, 14 May 2009 23:54:07 +0900
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Subject: Re: [PATCH] mmtom: Prevent shrinking of active anon lru list in case 
	of no swap space V3
From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Minchan Kim <barrioskmc@gmail.com>
Cc: MinChan Kim <minchan.kim@gmail.com>,
       Andrew Morton <akpm@linux-foundation.org>,
       LKML <linux-kernel@vger.kernel.org>, linux-mm <linux-mm@kvack.org>,
       Johannes Weiner <hannes@cmpxchg.org>, Rik van Riel <riel@redhat.com>
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2009/5/14 Minchan Kim <barrioskmc@gmail.com>:
> On Thu, May 14, 2009 at 11:27 PM, KOSAKI Motohiro
> <kosaki.motohiro@jp.fujitsu.com> wrote:
>>>  mm/vmscan.c |    2 +-
>>>  1 files changed, 1 insertions(+), 1 deletions(-)
>>>
>>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>>> index 2f9d555..621708f 100644
>>> --- a/mm/vmscan.c
>>> +++ b/mm/vmscan.c
>>> @@ -1577,7 +1577,7 @@ static void shrink_zone(int priority, struct zone *zone,
>>>         * Even if we did not try to evict anon pages at all, we want to
>>>         * rebalance the anon lru active/inactive ratio.
>>>         */
>>> -       if (inactive_anon_is_low(zone, sc))
>>> +       if (inactive_anon_is_low(zone, sc) && nr_swap_pages > 0)
>>>                shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);
>>
>>
>>       if (nr_swap_pages > 0 && inactive_anon_is_low(zone, sc))
>>
>> is better?
>> compiler can't swap evaluate order around &&.
>
> If GCC optimizes away that branch with CONFIG_SWAP=n as Rik mentioned,
> we don't have a concern.

ok. I ack this.