linux-kernel - Re: [PATCH] memcg: modify swap accounting function to support THP

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Date:	Fri, 11 Jan 2013 11:45:31 +0800
From:	Sha Zhengju <handai.szj@...il.com>
To:	Michal Hocko <mhocko@...e.cz>
Cc:	linux-kernel@...r.kernel.org, cgroups@...r.kernel.org,
	linux-mm@...ck.org, akpm@...ux-foundation.org,
	kamezawa.hiroyu@...fujitsu.com, Sha Zhengju <handai.szj@...bao.com>
Subject: Re: [PATCH] memcg: modify swap accounting function to support THP

On Thu, Jan 10, 2013 at 9:39 PM, Michal Hocko <mhocko@...e.cz> wrote:
> On Thu 10-01-13 19:43:58, Sha Zhengju wrote:
>> From: Sha Zhengju <handai.szj@...bao.com>
>
> THP are not swapped out because they are split before so this change
> doesn't make much sense to me.

Yes... I have been puzzled by 'nr_pages' in __mem_cgroup_uncharge_common..
Sorry for the noise. : )

>
>> Signed-off-by: Sha Zhengju <handai.szj@...bao.com>
>> ---
>>  mm/memcontrol.c |   13 ++++++-------
>>  1 file changed, 6 insertions(+), 7 deletions(-)
>>
>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>> index 3817460..674cf21 100644
>> --- a/mm/memcontrol.c
>> +++ b/mm/memcontrol.c
>> @@ -914,10 +914,9 @@ static long mem_cgroup_read_stat(struct mem_cgroup *memcg,
>>  }
>>
>>  static void mem_cgroup_swap_statistics(struct mem_cgroup *memcg,
>> -                                      bool charge)
>> +                                      int nr_pages)
>>  {
>> -     int val = (charge) ? 1 : -1;
>> -     this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], val);
>> +     this_cpu_add(memcg->stat->count[MEM_CGROUP_STAT_SWAP], nr_pages);
>>  }
>>
>>  static unsigned long mem_cgroup_read_events(struct mem_cgroup *memcg,
>> @@ -4107,7 +4106,7 @@ __mem_cgroup_uncharge_common(struct page *page, enum charge_type ctype,
>>        */
>>       memcg_check_events(memcg, page);
>>       if (do_swap_account && ctype == MEM_CGROUP_CHARGE_TYPE_SWAPOUT) {
>> -             mem_cgroup_swap_statistics(memcg, true);
>> +             mem_cgroup_swap_statistics(memcg, nr_pages);
>>               mem_cgroup_get(memcg);
>>       }
>>       /*
>> @@ -4238,7 +4237,7 @@ void mem_cgroup_uncharge_swap(swp_entry_t ent)
>>                */
>>               if (!mem_cgroup_is_root(memcg))
>>                       res_counter_uncharge(&memcg->memsw, PAGE_SIZE);
>> -             mem_cgroup_swap_statistics(memcg, false);
>> +             mem_cgroup_swap_statistics(memcg, -1);
>>               mem_cgroup_put(memcg);
>>       }
>>       rcu_read_unlock();
>> @@ -4267,8 +4266,8 @@ static int mem_cgroup_move_swap_account(swp_entry_t entry,
>>       new_id = css_id(&to->css);
>>
>>       if (swap_cgroup_cmpxchg(entry, old_id, new_id) == old_id) {
>> -             mem_cgroup_swap_statistics(from, false);
>> -             mem_cgroup_swap_statistics(to, true);
>> +             mem_cgroup_swap_statistics(from, -1);
>> +             mem_cgroup_swap_statistics(to, 1);
>>               /*
>>                * This function is only called from task migration context now.
>>                * It postpones res_counter and refcount handling till the end
>> --
>> 1.7.9.5
>>
>> --
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>
> --
> Michal Hocko
> SUSE Labs



-- 
Thanks,
Sha
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