Re: [PATCH v5 2/4] memcg: move memcg reclaimable page into tail of inactive list

[Minchan Kim <minchan.kim@gmail.com>]

On Fri, Feb 18, 2011 at 1:16 PM, Hiroyuki Kamezawa
<kamezawa.hiroyuki@gmail.com> wrote:
> 2011/2/18 Minchan Kim <minchan.kim@gmail.com>:
>> Hi Kame,
>>
>> On Fri, Feb 18, 2011 at 1:04 AM, KAMEZAWA Hiroyuki
>> <kamezawa.hiroyu@jp.fujitsu.com> wrote:
>>> On Fri, 18 Feb 2011 00:08:20 +0900
>>> Minchan Kim <minchan.kim@gmail.com> wrote:
>>>
>>>> The rotate_reclaimable_page function moves just written out
>>>> pages, which the VM wanted to reclaim, to the end of the
>>>> inactive list.  That way the VM will find those pages first
>>>> next time it needs to free memory.
>>>> This patch apply the rule in memcg.
>>>> It can help to prevent unnecessary working page eviction of memcg.
>>>>
>>>> Acked-by: Balbir Singh <balbir@linux.vnet.ibm.com>
>>>> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>>>> Reviewed-by: Rik van Riel <riel@redhat.com>
>>>> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
>>>> Cc: Johannes Weiner <hannes@cmpxchg.org>
>>>> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
>>>> ---
>>>> Changelog since v4:
>>>>  - add acked-by and reviewed-by
>>>>  - change description - suggested by Rik
>>>>
>>>>  include/linux/memcontrol.h |    6 ++++++
>>>>  mm/memcontrol.c            |   27 +++++++++++++++++++++++++++
>>>>  mm/swap.c                  |    3 ++-
>>>>  3 files changed, 35 insertions(+), 1 deletions(-)
>>>>
>>>> diff --git a/include/linux/memcontrol.h b/include/linux/memcontrol.h
>>>> index 3da48ae..5a5ce70 100644
>>>> --- a/include/linux/memcontrol.h
>>>> +++ b/include/linux/memcontrol.h
>>>> @@ -62,6 +62,7 @@ extern int mem_cgroup_cache_charge(struct page *page, struct mm_struct *mm,
>>>>                                       gfp_t gfp_mask);
>>>>  extern void mem_cgroup_add_lru_list(struct page *page, enum lru_list lru);
>>>>  extern void mem_cgroup_del_lru_list(struct page *page, enum lru_list lru);
>>>> +extern void mem_cgroup_rotate_reclaimable_page(struct page *page);
>>>>  extern void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru);
>>>>  extern void mem_cgroup_del_lru(struct page *page);
>>>>  extern void mem_cgroup_move_lists(struct page *page,
>>>> @@ -215,6 +216,11 @@ static inline void mem_cgroup_del_lru_list(struct page *page, int lru)
>>>>       return ;
>>>>  }
>>>>
>>>> +static inline inline void mem_cgroup_rotate_reclaimable_page(struct page *page)
>>>> +{
>>>> +     return ;
>>>> +}
>>>> +
>>>>  static inline void mem_cgroup_rotate_lru_list(struct page *page, int lru)
>>>>  {
>>>>       return ;
>>>> diff --git a/mm/memcontrol.c b/mm/memcontrol.c
>>>> index 686f1ce..ab8bdff 100644
>>>> --- a/mm/memcontrol.c
>>>> +++ b/mm/memcontrol.c
>>>> @@ -813,6 +813,33 @@ void mem_cgroup_del_lru(struct page *page)
>>>>       mem_cgroup_del_lru_list(page, page_lru(page));
>>>>  }
>>>>
>>>> +/*
>>>> + * Writeback is about to end against a page which has been marked for immediate
>>>> + * reclaim.  If it still appears to be reclaimable, move it to the tail of the
>>>> + * inactive list.
>>>> + */
>>>> +void mem_cgroup_rotate_reclaimable_page(struct page *page)
>>>> +{
>>>> +     struct mem_cgroup_per_zone *mz;
>>>> +     struct page_cgroup *pc;
>>>> +     enum lru_list lru = page_lru_base_type(page);
>>>> +
>>>> +     if (mem_cgroup_disabled())
>>>> +             return;
>>>> +
>>>> +     pc = lookup_page_cgroup(page);
>>>> +     /*
>>>> +      * Used bit is set without atomic ops but after smp_wmb().
>>>> +      * For making pc->mem_cgroup visible, insert smp_rmb() here.
>>>> +      */
>>>> +     smp_rmb();
>>>> +     /* unused or root page is not rotated. */
>>>> +     if (!PageCgroupUsed(pc) || mem_cgroup_is_root(pc->mem_cgroup))
>>>> +             return;
>>>> +     mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
>>>> +     list_move_tail(&pc->lru, &mz->lists[lru]);
>>>> +}
>>>> +
>>>
>>> Hmm, I'm sorry I misunderstand this. IIUC, page_lru_base_type() always returns
>>> LRU_INACTIVE_XXX and this function may move page from active LRU to inactive LRU.
>>>
>>> Then, LRU counters for memcg should be updated.
>>
>> Goal of mem_cgroup_rotate_reclaimable_page is same with rotate_reclaimable_page.
>> It means the page was already in inactive list.
>> Look at the check !PageActive(page).
>
> Hmm, ok. If so, could you change
>
> page_lru_base_type() -> page_lru() ?
>
> It's misleading.

No problem. Will resend.

>
> Thanks,
> -Kame
>



-- 
Kind regards,
Minchan Kim

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