Re: [RFC][PATCH 5/5] memcg softlimit hooks to kswapd

[KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>]

On Thu, 12 Mar 2009 10:00:08 +0900
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> wrote:

> This patch needs MORE investigation...
> 
> ==
> From: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> 
> This patch adds hooks for memcg's softlimit to kswapd().
> 
> Softlimit handler is called...
>   - before generic shrink_zone() is called.
>   - # of pages to be scanned depends on priority.
>   - If not enough progress, selected memcg will be moved to UNUSED queue.
>   - at each call for balance_pgdat(), softlimit queue is rebalanced.
> 
> Changelog: v3 -> v4
>  - move "sc" as local variable
> 
> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
> ---
>  mm/vmscan.c |   52 ++++++++++++++++++++++++++++++++++++++++++++++++++++
>  1 file changed, 52 insertions(+)
> 
> Index: mmotm-2.6.29-Mar10/mm/vmscan.c
> ===================================================================
> --- mmotm-2.6.29-Mar10.orig/mm/vmscan.c
> +++ mmotm-2.6.29-Mar10/mm/vmscan.c
> @@ -1733,6 +1733,49 @@ unsigned long try_to_free_mem_cgroup_pag
>  }
>  #endif
>  
> +static void shrink_zone_softlimit(struct zone *zone, int order, int priority,
> +			   int target, int end_zone)
> +{
> +	int scan = SWAP_CLUSTER_MAX;
> +	int nid = zone->zone_pgdat->node_id;
> +	int zid = zone_idx(zone);
> +	struct mem_cgroup *mem;
> +	struct scan_control sc =  {
> +		.gfp_mask = GFP_KERNEL,
> +		.may_writepage = !laptop_mode,
> +		.swap_cluster_max = SWAP_CLUSTER_MAX,
> +		.may_unmap = 1,
> +		.swappiness = vm_swappiness,
> +		.order = order,
> +		.mem_cgroup = NULL,
> +		.isolate_pages = mem_cgroup_isolate_pages,
> +	};
> +
> +	scan = target * 2;
> +
> +	sc.nr_scanned = 0;
> +	sc.nr_reclaimed = 0;
> +	while (scan > 0) {
> +		if (zone_watermark_ok(zone, order, target, end_zone, 0))
> +			break;
> +		mem = mem_cgroup_schedule(nid, zid);
> +		if (!mem)
> +			return;
> +		sc.mem_cgroup = mem;
> +
> +		sc.nr_reclaimed = 0;
needs
  sc.nr_scanned = 0;
...
-Kame
> +		shrink_zone(priority, zone, &sc);
> +
> +		if (sc.nr_reclaimed >= SWAP_CLUSTER_MAX/2)
> +			mem_cgroup_schedule_end(nid, zid, mem, true);
> +		else
> +			mem_cgroup_schedule_end(nid, zid, mem, false);
> +
> +		scan -= sc.nr_scanned;
> +	}
> +
> +	return;
> +}
>  /*
>   * For kswapd, balance_pgdat() will work across all this node's zones until
>   * they are all at pages_high.
> @@ -1776,6 +1819,8 @@ static unsigned long balance_pgdat(pg_da
>  	 */
>  	int temp_priority[MAX_NR_ZONES];
>  
> +	/* Refill softlimit queue */
> +	mem_cgroup_reschedule_all(pgdat->node_id);
>  loop_again:
>  	total_scanned = 0;
>  	sc.nr_reclaimed = 0;
> @@ -1856,6 +1901,13 @@ loop_again:
>  					       end_zone, 0))
>  				all_zones_ok = 0;
>  			temp_priority[i] = priority;
> +
> +			/*
> +			 * Try soft limit at first.  This reclaims page
> +			 * with regard to user's hint.
> +			 */
> +			shrink_zone_softlimit(zone, order, priority,
> +					       8 * zone->pages_high, end_zone);
>  			sc.nr_scanned = 0;
>  			note_zone_scanning_priority(zone, priority);
>  			/*
> 
>