Re: [RFC][PATCH 3/4] memcg: softlimit caller via kswapd

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

On Thu, 12 Mar 2009 09:05:43 +0900 (JST)
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com> wrote:

> Hi Balbir-san,
> 
> > Looks like a dirty hack, replacing sc-> fields this way. I've
> > experimented a lot with per zone balancing and soft limits and it does
> > not work well. The reasons
> > 
> > 1. zone watermark balancing has a different goal than soft limit. Soft
> > limits are more of a mem cgroup feature rather than node/zone feature.
> > IIRC, you called reclaim as hot-path for soft limit reclaim, my
> > experimentation is beginning to show changed behaviour
> > 
> > On a system with 4 CPUs and 4 Nodes, I find all CPUs spending time
> > doing reclaim, putting the hook in the reclaim path, makes the reclaim
> > dependent on the number of tasks and contention.
> > 
> > What does your test data/experimentation show?
> 
> you pointed out mainline kernel bug, not kamezawa patch's bug ;-)
> Could you please try following patch?
> 
> sorry, this is definitly my fault.
> 
> 
Thank you!

-Kame


> ---
>  mm/vmscan.c |    2 +-
>  1 files changed, 1 insertions(+), 1 deletions(-)
> 
> diff --git a/mm/vmscan.c b/mm/vmscan.c
> index bfd853b..15f7737 100644
> --- a/mm/vmscan.c
> +++ b/mm/vmscan.c
> @@ -1470,7 +1470,7 @@ static void shrink_zone(int priority, struct zone *zone,
>  		int file = is_file_lru(l);
>  		int scan;
>  
> -		scan = zone_page_state(zone, NR_LRU_BASE + l);
> +		scan = zone_nr_pages(zone, sc, l);
>  		if (priority) {
>  			scan >>= priority;
>  			scan = (scan * percent[file]) / 100;
> -- 
> 1.6.0.6
> 
> 
> 
> 

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