Re: [PATCH 1/2] memcg, oom: provide more precise dump info while memcg oom happening

[Sha Zhengju <handai.szj-Re5JQEeQqe8AvxtiuMwx3w@public.gmane.org>]

On 11/08/2012 06:17 AM, Michal Hocko wrote:
> On Wed 07-11-12 16:41:36, Sha Zhengju wrote:
>> From: Sha Zhengju<handai.szj-3b8fjiQLQpfQT0dZR+AlfA@public.gmane.org>
>>
>> Current, when a memcg oom is happening the oom dump messages is still global
>> state and provides few useful info for users. This patch prints more pointed
>> memcg page statistics for memcg-oom.
>>
>> Signed-off-by: Sha Zhengju<handai.szj-3b8fjiQLQpfQT0dZR+AlfA@public.gmane.org>
>> Cc: Michal Hocko<mhocko-AlSwsSmVLrQ@public.gmane.org>
>> Cc: KAMEZAWA Hiroyuki<kamezawa.hiroyu-+CUm20s59erQFUHtdCDX3A@public.gmane.org>
>> Cc: David Rientjes<rientjes-hpIqsD4AKlfQT0dZR+AlfA@public.gmane.org>
>> Cc: Andrew Morton<akpm-de/tnXTf+JLsfHDXvbKv3WD2FQJk+8+b@public.gmane.org>
>> ---
>>   mm/memcontrol.c |   71 ++++++++++++++++++++++++++++++++++++++++++++++++-------
>>   mm/oom_kill.c   |    6 +++-
>>   2 files changed, 66 insertions(+), 11 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 0eab7d5..2df5e72 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
> [...]
>> @@ -1501,8 +1509,59 @@ static void move_unlock_mem_cgroup(struct mem_cgroup *memcg,
>>   	spin_unlock_irqrestore(&memcg->move_lock, *flags);
>>   }
>>
>> +#define K(x) ((x)<<  (PAGE_SHIFT-10))
>> +static void mem_cgroup_print_oom_stat(struct mem_cgroup *memcg)
>> +{
>> +	struct mem_cgroup *mi;
>> +	unsigned int i;
>> +
>> +	if (!memcg->use_hierarchy&&  memcg != root_mem_cgroup) {
>> +		for (i = 0; i<  MEM_CGROUP_STAT_NSTATS; i++) {
>> +			if (i == MEM_CGROUP_STAT_SWAP&&  !do_swap_account)
>> +				continue;
>> +			printk(KERN_CONT "%s:%ldKB ", mem_cgroup_stat_names[i],
>> +				K(mem_cgroup_read_stat(memcg, i)));
>> +		}
>> +
>> +		for (i = 0; i<  MEM_CGROUP_EVENTS_NSTATS; i++)
>> +			printk(KERN_CONT "%s:%lu ", mem_cgroup_events_names[i],
>> +				mem_cgroup_read_events(memcg, i));
>> +
>> +		for (i = 0; i<  NR_LRU_LISTS; i++)
>> +			printk(KERN_CONT "%s:%luKB ", mem_cgroup_lru_names[i],
>> +				K(mem_cgroup_nr_lru_pages(memcg, BIT(i))));
>> +	} else {
>> +
>> +		for (i = 0; i<  MEM_CGROUP_STAT_NSTATS; i++) {
>> +			long long val = 0;
>> +
>> +			if (i == MEM_CGROUP_STAT_SWAP&&  !do_swap_account)
>> +				continue;
>> +			for_each_mem_cgroup_tree(mi, memcg)
>> +				val += mem_cgroup_read_stat(mi, i);
>> +			printk(KERN_CONT "%s:%lldKB ", mem_cgroup_stat_names[i], K(val));
>> +		}
>> +
>> +		for (i = 0; i<  MEM_CGROUP_EVENTS_NSTATS; i++) {
>> +			unsigned long long val = 0;
>> +
>> +			for_each_mem_cgroup_tree(mi, memcg)
>> +				val += mem_cgroup_read_events(mi, i);
>> +			printk(KERN_CONT "%s:%llu ",
>> +				mem_cgroup_events_names[i], val);
>> +		}
>> +
>> +		for (i = 0; i<  NR_LRU_LISTS; i++) {
>> +			unsigned long long val = 0;
>> +
>> +			for_each_mem_cgroup_tree(mi, memcg)
>> +				val += mem_cgroup_nr_lru_pages(mi, BIT(i));
>> +			printk(KERN_CONT "%s:%lluKB ", mem_cgroup_lru_names[i], K(val));
>> +		}
>> +	}
> This is just plain ugly. for_each_mem_cgroup_tree is use_hierarchy aware
> and there is no need for if (use_hierarchy) part.
> memcg != root_mem_cgroup test doesn't make much sense as well because we
> call that a global oom killer ;)

Yes... bitterly did I repent the patch... The else-part of 
for_each_mem_cgroup_tree
is enough for hierarchy. I'll send a update one later.
Sorry for the noise. : (


Thanks,
Sha