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

[Sha Zhengju]

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@xxxxxxxxxx>
> >
> > 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@xxxxxxxxxx>
> > Cc: Michal Hocko<mhocko@xxxxxxx>
> > Cc: KAMEZAWA Hiroyuki<kamezawa.hiroyu@xxxxxxxxxxxxxx>
> > Cc: David Rientjes<rientjes@xxxxxxxxxx>
> > Cc: Andrew Morton<akpm@xxxxxxxxxxxxxxxxxxxx>
> > ---
> >   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


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