linux-kernel - Re: [PATCH RFC] mm/memcg: calculate max hierarchy limit number instead of min

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Message-ID: <20120712101827.GD21013@tiehlicka.suse.cz>
Date:	Thu, 12 Jul 2012 12:18:27 +0200
From:	Michal Hocko <mhocko@...e.cz>
To:	Wanpeng Li <liwp.linux@...il.com>
Cc:	linux-mm@...ck.org, Johannes Weiner <hannes@...xchg.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrew Morton <akpm@...ux-foundation.org>,
	cgroups@...r.kernel.org, linux-kernel@...r.kernel.org
Subject: Re: [PATCH RFC] mm/memcg: calculate max hierarchy limit number
 instead of min

On Thu 12-07-12 17:32:11, Wanpeng Li wrote:
> On Wed, Jul 11, 2012 at 03:47:57PM +0200, Michal Hocko wrote:
> >On Wed 11-07-12 21:24:41, Wanpeng Li wrote:
> >> From: Wanpeng Li <liwp@...ux.vnet.ibm.com>
> >> 
> >> Since hierachical_memory_limit shows "of bytes of memory limit with
> >> regard to hierarchy under which the memory cgroup is", the count should
> >> calculate max hierarchy limit when use_hierarchy in order to show hierarchy
> >> subtree limit. hierachical_memsw_limit is the same case.
> >
> >No the patch is wrong. The hierarchical limit says when we start
> >reclaiming in the hierarchy and that one is triggered on smallest limit
> >up the way to the hierarchy root.
> 
> I see function mem_cgroup_hierachy_reclaim is removal, and hierarchical
> reclaim is still work? 

I am not aware of that.

> Could you explain me how it works in details, thank you for your time
> Michal.

I am not sure I understand what you are interested in. 

> 
> Thanks & Best Regards,
> Wanpeng Li
> >
> >What are you trying to accomplish here?
> >
> >> Signed-off-by: Wanpeng Li <liwp.linux@...il.com>
> >> ---
> >>  mm/memcontrol.c |   14 +++++++-------
> >>  1 files changed, 7 insertions(+), 7 deletions(-)
> >> 
> >> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
> >> index 69a7d45..6392c0a 100644
> >> --- a/mm/memcontrol.c
> >> +++ b/mm/memcontrol.c
> >> @@ -3929,10 +3929,10 @@ static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
> >>  		unsigned long long *mem_limit, unsigned long long *memsw_limit)
> >>  {
> >>  	struct cgroup *cgroup;
> >> -	unsigned long long min_limit, min_memsw_limit, tmp;
> >> +	unsigned long long max_limit, max_memsw_limit, tmp;
> >>  
> >> -	min_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
> >> -	min_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> >> +	max_limit = res_counter_read_u64(&memcg->res, RES_LIMIT);
> >> +	max_memsw_limit = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> >>  	cgroup = memcg->css.cgroup;
> >>  	if (!memcg->use_hierarchy)
> >>  		goto out;
> >> @@ -3943,13 +3943,13 @@ static void memcg_get_hierarchical_limit(struct mem_cgroup *memcg,
> >>  		if (!memcg->use_hierarchy)
> >>  			break;
> >>  		tmp = res_counter_read_u64(&memcg->res, RES_LIMIT);
> >> -		min_limit = min(min_limit, tmp);
> >> +		max_limit = max(max_limit, tmp);
> >>  		tmp = res_counter_read_u64(&memcg->memsw, RES_LIMIT);
> >> -		min_memsw_limit = min(min_memsw_limit, tmp);
> >> +		max_memsw_limit = max(max_memsw_limit, tmp);
> >>  	}
> >>  out:
> >> -	*mem_limit = min_limit;
> >> -	*memsw_limit = min_memsw_limit;
> >> +	*mem_limit = max_limit;
> >> +	*memsw_limit = max_memsw_limit;
> >>  }
> >>  
> >>  static int mem_cgroup_reset(struct cgroup *cont, unsigned int event)
> >> -- 
> >> 1.7.5.4
> >> 
> >
> >-- 
> >Michal Hocko
> >SUSE Labs
> >SUSE LINUX s.r.o.
> >Lihovarska 1060/12
> >190 00 Praha 9    
> >Czech Republic

-- 
Michal Hocko
SUSE Labs
SUSE LINUX s.r.o.
Lihovarska 1060/12
190 00 Praha 9    
Czech Republic
--
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