linux-kernel - Re: [PATCH 2/2] memcg, vmscan: Fix forced scan of anonymous pages

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Date:	Mon, 04 Aug 2014 11:56:26 +0200
From:	Jerome Marchand <jmarchan@...hat.com>
To:	Michal Hocko <mhocko@...e.cz>, Johannes Weiner <hannes@...xchg.org>
CC:	linux-mm@...ck.org, linux-kernel@...r.kernel.org,
	Andrew Morton <akpm@...ux-foundation.org>,
	Mel Gorman <mgorman@...e.de>, Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH 2/2] memcg, vmscan: Fix forced scan of anonymous pages

On 08/01/2014 08:52 PM, Michal Hocko wrote:
> On Fri 01-08-14 14:45:25, Johannes Weiner wrote:
>> On Thu, Jul 31, 2014 at 02:30:26PM +0200, Michal Hocko wrote:
>>> On Thu 31-07-14 13:49:45, Jerome Marchand wrote:
>>>> @@ -1950,8 +1950,11 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
>>>>  	 */
>>>>  	if (global_reclaim(sc)) {
>>>>  		unsigned long free = zone_page_state(zone, NR_FREE_PAGES);
>>>> +		unsigned long zonefile =
>>>> +			zone_page_state(zone, NR_LRU_BASE + LRU_ACTIVE_FILE) +
>>>> +			zone_page_state(zone, NR_LRU_BASE + LRU_INACTIVE_FILE);
>>>>  
>>>> -		if (unlikely(file + free <= high_wmark_pages(zone))) {
>>>> +		if (unlikely(zonefile + free <= high_wmark_pages(zone))) {
>>>>  			scan_balance = SCAN_ANON;
>>>>  			goto out;
>>>>  		}
>>>
>>> You could move file and anon further down when we actually use them.

I missed that comment. Thanks for the cleanup Johannes!

>>
>> Agreed with that.  Can we merge this into the original patch?
>>
>> ---
>> From e49bef8d2751d9b27f1733e3e0eced325ffce700 Mon Sep 17 00:00:00 2001
>> From: Johannes Weiner <hannes@...xchg.org>
>> Date: Fri, 1 Aug 2014 10:48:26 -0400
>> Subject: [patch] memcg, vmscan: Fix forced scan of anonymous pages fix -
>>  cleanups
>>
>> o Use enum zone_stat_item symbols directly to select zone stats,
>>   rather than NR_LRU_BASE plus LRU index
>>
>> o scanned/rotated scaling is the only user of the lruvec anon/file
>>   counters, so move the reads of those values to right before that
>>
>> Signed-off-by: Johannes Weiner <hannes@...xchg.org>
> 
> Yes, please.
> Acked-by: Michal Hocko <mhocko@...e.cz>

Acked-by: Jerome Marchand <jmarchan@...hat.com>

> 
> Thanks!
> 
>> ---
>>  mm/vmscan.c | 23 +++++++++++++----------
>>  1 file changed, 13 insertions(+), 10 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index b3f629bdf4fe..2836b5373b2e 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1934,11 +1934,6 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
>>  		goto out;
>>  	}
>>  
>> -	anon  = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
>> -		get_lru_size(lruvec, LRU_INACTIVE_ANON);
>> -	file  = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
>> -		get_lru_size(lruvec, LRU_INACTIVE_FILE);
>> -
>>  	/*
>>  	 * Prevent the reclaimer from falling into the cache trap: as
>>  	 * cache pages start out inactive, every cache fault will tip
>> @@ -1949,12 +1944,14 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
>>  	 * anon pages.  Try to detect this based on file LRU size.
>>  	 */
>>  	if (global_reclaim(sc)) {
>> -		unsigned long free = zone_page_state(zone, NR_FREE_PAGES);
>> -		unsigned long zonefile =
>> -			zone_page_state(zone, NR_LRU_BASE + LRU_ACTIVE_FILE) +
>> -			zone_page_state(zone, NR_LRU_BASE + LRU_INACTIVE_FILE);
>> +		unsigned long zonefile;
>> +		unsigned long zonefree;
>> +
>> +		zonefree = zone_page_state(zone, NR_FREE_PAGES);
>> +		zonefile = zone_page_state(zone, NR_ACTIVE_FILE) +
>> +			   zone_page_state(zone, NR_INACTIVE_FILE);
>>  
>> -		if (unlikely(zonefile + free <= high_wmark_pages(zone))) {
>> +		if (unlikely(zonefile + zonefree <= high_wmark_pages(zone))) {
>>  			scan_balance = SCAN_ANON;
>>  			goto out;
>>  		}
>> @@ -1989,6 +1986,12 @@ static void get_scan_count(struct lruvec *lruvec, int swappiness,
>>  	 *
>>  	 * anon in [0], file in [1]
>>  	 */
>> +
>> +	anon  = get_lru_size(lruvec, LRU_ACTIVE_ANON) +
>> +		get_lru_size(lruvec, LRU_INACTIVE_ANON);
>> +	file  = get_lru_size(lruvec, LRU_ACTIVE_FILE) +
>> +		get_lru_size(lruvec, LRU_INACTIVE_FILE);
>> +
>>  	spin_lock_irq(&zone->lru_lock);
>>  	if (unlikely(reclaim_stat->recent_scanned[0] > anon / 4)) {
>>  		reclaim_stat->recent_scanned[0] /= 2;
>> -- 
>> 2.0.3
>>
> 



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