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

[Wanpeng Li <liwp.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

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-23VcF4HTsmIX0ybBhKVfKdBPR1lH4CV8@public.gmane.org>
>> 
>> 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? Could you explain me how it works in details, 
thank you for your time Michal.

Thanks & Best Regards,
Wanpeng Li
>
>What are you trying to accomplish here?
>
>> Signed-off-by: Wanpeng Li <liwp.linux-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>
>> ---
>>  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