Re: [PATCH 4/4] Memory controller soft limit reclaim on contention (v5)

[Balbir Singh <balbir@linux.vnet.ibm.com>]

* KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com> [2009-03-13 15:51:25]:

> Balbir Singh wrote:
> > Feature: Implement reclaim from groups over their soft limit
> >
> > From: Balbir Singh <balbir@linux.vnet.ibm.com>
> 
> > +unsigned long mem_cgroup_soft_limit_reclaim(struct zonelist *zl, gfp_t
> > gfp_mask)
> > +{
> > +	unsigned long nr_reclaimed = 0;
> > +	struct mem_cgroup *mem;
> > +	unsigned long flags;
> > +	unsigned long reclaimed;
> > +
> > +	/*
> > +	 * This loop can run a while, specially if mem_cgroup's continuously
> > +	 * keep exceeding their soft limit and putting the system under
> > +	 * pressure
> > +	 */
> > +	do {
> > +		mem = mem_cgroup_largest_soft_limit_node();
> > +		if (!mem)
> > +			break;
> > +
> > +		reclaimed = mem_cgroup_hierarchical_reclaim(mem, zl,
> > +						gfp_mask,
> > +						MEM_CGROUP_RECLAIM_SOFT);
> > +		nr_reclaimed += reclaimed;
> > +		spin_lock_irqsave(&memcg_soft_limit_tree_lock, flags);
> > +		mem->usage_in_excess = res_counter_soft_limit_excess(&mem->res);
> > +		__mem_cgroup_remove_exceeded(mem);
> > +		if (mem->usage_in_excess)
> > +			__mem_cgroup_insert_exceeded(mem);
> > +		spin_unlock_irqrestore(&memcg_soft_limit_tree_lock, flags);
> > +		css_put(&mem->css);
> > +		cond_resched();
> > +	} while (!nr_reclaimed);
> > +	return nr_reclaimed;
> > +}
> > +
>  Why do you never consider bad corner case....
>  As I wrote many times, "order of global usage" doesn't mean the
>  biggest user of memcg containes memory in zones which we want.
>  So, please don't pust "mem" back to RB-tree if reclaimed is 0.
> 
>  This routine seems toooo bad as v4.

Are you talking about cases where a particular mem cgroup never
allocated from a node? Thanks.. let me take a look at it

-- 
	Balbir

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