linux-kernel - Re: [PATCH 0/4] Memory controller soft limit patches (v3)

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Date:	Thu, 5 Mar 2009 18:13:23 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc:	balbir@...ux.vnet.ibm.com, linux-mm@...ck.org,
	Sudhir Kumar <skumar@...ux.vnet.ibm.com>,
	YAMAMOTO Takashi <yamamoto@...inux.co.jp>,
	Bharata B Rao <bharata@...ibm.com>,
	Paul Menage <menage@...gle.com>, lizf@...fujitsu.com,
	linux-kernel@...r.kernel.org,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	David Rientjes <rientjes@...gle.com>,
	Pavel Emelianov <xemul@...nvz.org>,
	Dhaval Giani <dhaval@...ux.vnet.ibm.com>,
	Rik van Riel <riel@...hat.com>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 0/4] Memory controller soft limit patches (v3)


I wrote almost all concerns are addressed but following part is a concern.

On Thu, 5 Mar 2009 18:04:10 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com> wrote:

> @@ -1758,6 +1778,7 @@ static unsigned long balance_pgdat(pg_da
>  {
>  	int all_zones_ok;
>  	int priority;
> +	int nid = pgdat->node_id;
>  	int i;
>  	unsigned long total_scanned;
>  	struct reclaim_state *reclaim_state = current->reclaim_state;
> @@ -1785,6 +1806,8 @@ loop_again:
>  	for (i = 0; i < pgdat->nr_zones; i++)
>  		temp_priority[i] = DEF_PRIORITY;
>  
> +	mem_cgroup_update_softlimit_hint(nid);
> +
>  	for (priority = DEF_PRIORITY; priority >= 0; priority--) {
>  		int end_zone = 0;	/* Inclusive.  0 = ZONE_DMA */
>  		unsigned long lru_pages = 0;
> @@ -1863,8 +1886,17 @@ loop_again:
>  			 * zone has way too many pages free already.
>  			 */
>  			if (!zone_watermark_ok(zone, order, 8*zone->pages_high,
> -						end_zone, 0))
> -				shrink_zone(priority, zone, &sc);
> +					       end_zone, 0)) {
> +				/*
> +				 * If priority is not so bad, try softlimit
> +				 * of memcg.
> +				 */
> +				if (!(priority < DEF_PRIORITY - 2))
> +					softlimit_shrink_zone(nid, i,
> +							 priority, zone, &sc);
> +				else
> +					shrink_zone(priority, zone, &sc);
> +			}
>  			reclaim_state->reclaimed_slab = 0;
>  			nr_slab = shrink_slab(sc.nr_scanned, GFP_KERNEL,
>  						lru_pages);

This may increase priority to unexpected level, So, insert softlimit_shrink_zone()
before diving into this priority loop of balance_pgdat() may be better.

Thanks,
-Kame



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