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Message-ID: <AANLkTi=2s0efMsByDKAdVTWaouk0r84RQJVrwn2h6DG_@mail.gmail.com>
Date: Fri, 18 Feb 2011 09:14:34 +0900
From: Minchan Kim <minchan.kim@...il.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Andrew Morton <akpm@...ux-foundation.org>,
linux-mm <linux-mm@...ck.org>,
LKML <linux-kernel@...r.kernel.org>,
Steven Barrett <damentz@...uorix.net>,
Ben Gamari <bgamari.foss@...il.com>,
Peter Zijlstra <peterz@...radead.org>,
Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
Wu Fengguang <fengguang.wu@...el.com>,
Johannes Weiner <hannes@...xchg.org>,
Nick Piggin <npiggin@...nel.dk>,
Andrea Arcangeli <aarcange@...hat.com>,
Balbir Singh <balbir@...ux.vnet.ibm.com>
Subject: Re: [PATCH v5 2/4] memcg: move memcg reclaimable page into tail of
inactive list
Hi Kame,
On Fri, Feb 18, 2011 at 1:04 AM, KAMEZAWA Hiroyuki
<kamezawa.hiroyu@...fujitsu.com> wrote:
> On Fri, 18 Feb 2011 00:08:20 +0900
> Minchan Kim <minchan.kim@...il.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@...ux.vnet.ibm.com>
>> Acked-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
>> Reviewed-by: Rik van Riel <riel@...hat.com>
>> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
>> Cc: Johannes Weiner <hannes@...xchg.org>
>> Signed-off-by: Minchan Kim <minchan.kim@...il.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).
But if you want to make the function generally(ie, support
active->inactive, too), I don't mind it. but if you want it, let's
make rotate_reclaimable_page to general function, too. but now any
user doesn't use it.
Thanks for the careful review.
>
> Could you replace after lookup like this ?
>
> VM_BUG_ON(!PageCgroupAcctLRU(pc)) /* Implies this pages must be on some LRU */
> if (!PageCgroupUsed(pc))
> return;
> /* Used bit check is not necessary, because there is a case Unused page
> is lazily on LRU. We trust AcctLRU bit. */
> mz = page_cgroup_zoneinfo(pc->mem_cgroup, page);
> MEM_CGROUP_ZSTAT(mz, page_lru(page)) -= 1 << compound_order(page);
> MEM_CGROUP_ZSTAT(mz, lru) += 1 << compound_order(page)
> if (mem_cgroup_is_root(pc->mem_cgroup))
> return;
> list_move_tail(&pc->lru, &mz->lists[lru])
>
>
> Thanks,
> -Kame
>> void mem_cgroup_rotate_lru_list(struct page *page, enum lru_list lru)
>> {
>> struct mem_cgroup_per_zone *mz;
>> diff --git a/mm/swap.c b/mm/swap.c
>> index 4aea806..1b9e4eb 100644
>> --- a/mm/swap.c
>> +++ b/mm/swap.c
>> @@ -200,8 +200,9 @@ static void pagevec_move_tail(struct pagevec *pvec)
>> spin_lock(&zone->lru_lock);
>> }
>> if (PageLRU(page) && !PageActive(page) && !PageUnevictable(page)) {
>> - int lru = page_lru_base_type(page);
>> + enum lru_list lru = page_lru_base_type(page);
>> list_move_tail(&page->lru, &zone->lru[lru].list);
>> + mem_cgroup_rotate_reclaimable_page(page);
>> pgmoved++;
>> }
>> }
>> --
>> 1.7.1
>>
>> --
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>>
>
>
--
Kind regards,
Minchan Kim
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