linux-kernel - Re: [PATCH] mmtom: Prevent shrinking of active anon lru list in case of no swap space V2

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Date:	Thu, 14 May 2009 21:05:03 +0900
From:	Minchan Kim <minchan.kim@...il.com>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Johannes Weiner <hannes@...xchg.org>,
	Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH] mmtom: Prevent shrinking of active anon lru list in case 
	of no swap space V2

On Thu, May 14, 2009 at 8:44 PM, KOSAKI Motohiro
<kosaki.motohiro@...fujitsu.com> wrote:
>> >
>> > Changelog since V2
>> >  o Add new function - can_reclaim_anon : it tests anon_list can be reclaim
>> >
>> > Changelog since V1
>> >  o Use nr_swap_pages <= 0 in shrink_active_list to prevent scanning  of active anon list.
>> >
>> > Now shrink_active_list is called several places.
>> > But if we don't have a swap space, we can't reclaim anon pages.
>> > So, we don't need deactivating anon pages in anon lru list.
>> >
>> > Signed-off-by: Minchan Kim <minchan.kim@...il.com>
>> > Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
>> > Cc: Johannes Weiner <hannes@...xchg.org>
>> > Cc: Rik van Riel <riel@...hat.com>
>>
>> looks good to me. thanks :)
>
> Grr, my fault.
>
>
>
>>  static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
>>       struct zone *zone, struct scan_control *sc, int priority)
>>  {
>> @@ -1399,7 +1412,7 @@ static unsigned long shrink_list(enum lru_list lru, unsigned long nr_to_scan,
>>               return 0;
>>       }
>>
>> -     if (lru == LRU_ACTIVE_ANON && inactive_anon_is_low(zone, sc)) {
>> +     if (lru == LRU_ACTIVE_ANON && can_reclaim_anon(zone, sc)) {
>>               shrink_active_list(nr_to_scan, zone, sc, priority, file);
>>               return 0;
>
> you shouldn't do that. if nr_swap_pages==0, get_scan_ratio return anon=0%.
> then, this branch is unnecessary.
>

But, I think at last it can be happen following as.

1515         * Even if we did not try to evict anon pages at all, we want to
1516         * rebalance the anon lru active/inactive ratio.
1517         */
1518        if (inactive_anon_is_low(zone, sc))
1519                shrink_active_list(SWAP_CLUSTER_MAX, zone, sc, priority, 0);


>
>



-- 
Kinds regards,
Minchan Kim
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