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SubjectRe: Re: [PATCH 3/4] memcg: avoid account not-on-LRU pages
----- Original Message -----
>On Mon, 29 Sep 2008 19:23:39 +0900, KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fuj
itsu.com> wrote:
>> There are not-on-LRU pages which can be mapped and they are not worth to
>> be accounted. (becasue we can't shrink them and need dirty codes to handle
>> specical case) We'd like to make use of usual objrmap/radix-tree's protcol
>> and don't want to account out-of-vm's control pages.
>> When special_mapping_fault() is called, page->mapping is tend to be NULL
>> and it's charged as Anonymous page.
>> insert_page() also handles some special pages from drivers.
>>
>> This patch is for avoiding to account special pages.
>>
>> Changlog: v5 -> v6
>> - modified Documentation.
>> - fixed to charge only when a page is newly allocated.
>>
>> Signed-off-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
>>
>> Documentation/controllers/memory.txt | 24 ++++++++++++++++--------
>> mm/memory.c | 29 +++++++++++++----------------
>> mm/rmap.c | 4 ++--
>> 3 files changed, 31 insertions(+), 26 deletions(-)
>>
>> Index: mmotm-2.6.27-rc7+/mm/memory.c
>> ===================================================================
>> --- mmotm-2.6.27-rc7+.orig/mm/memory.c
>> +++ mmotm-2.6.27-rc7+/mm/memory.c
>> @@ -1323,18 +1323,14 @@ static int insert_page(struct vm_area_st
>> pte_t *pte;
>> spinlock_t *ptl;
>>
>> - retval = mem_cgroup_charge(page, mm, GFP_KERNEL);
>> - if (retval)
>> - goto out;
>> -
>> retval = -EINVAL;
>> if (PageAnon(page))
>> - goto out_uncharge;
>> + goto out;
>> retval = -ENOMEM;
>> flush_dcache_page(page);
>> pte = get_locked_pte(mm, addr, &ptl);
>> if (!pte)
>> - goto out_uncharge;
>> + goto out;
>> retval = -EBUSY;
>> if (!pte_none(*pte))
>> goto out_unlock;
>> @@ -1350,8 +1346,6 @@ static int insert_page(struct vm_area_st
>> return retval;
>> out_unlock:
>> pte_unmap_unlock(pte, ptl);
>> -out_uncharge:
>> - mem_cgroup_uncharge_page(page);
>> out:
>> return retval;
>> }
>> @@ -2463,6 +2457,7 @@ static int __do_fault(struct mm_struct *
>> struct page *page;
>> pte_t entry;
>> int anon = 0;
>> + int charged = 0;
>> struct page *dirty_page = NULL;
>> struct vm_fault vmf;
>> int ret;
>> @@ -2503,6 +2498,12 @@ static int __do_fault(struct mm_struct *
>> ret = VM_FAULT_OOM;
>> goto out;
>> }
>> + if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
>> + ret = VM_FAULT_OOM;
>> + page_cache_release(page);
>> + goto out;
>> + }
>> + charged = 1;
>> /*
>> * Don't let another task, with possibly unlocked vma,
>> * keep the mlocked page.
>> @@ -2543,11 +2544,6 @@ static int __do_fault(struct mm_struct *
>>
>> }
>>
>> - if (mem_cgroup_charge(page, mm, GFP_KERNEL)) {
>> - ret = VM_FAULT_OOM;
>> - goto out;
>> - }
>> -
>> page_table = pte_offset_map_lock(mm, pmd, address, &ptl);
>>
>> /*
>> @@ -2585,10 +2581,11 @@ static int __do_fault(struct mm_struct *
>> /* no need to invalidate: a not-present page won't be cached */
>> update_mmu_cache(vma, address, entry);
>> } else {
>> - mem_cgroup_uncharge_page(page);
>> - if (anon)
>> + if (charged)
>> + mem_cgroup_uncharge_page(page);
>> + if (anon) {
>> page_cache_release(page);
>> - else
>> + } else
>> anon = 1; /* no anon but release faulted_page */
>> }
>>
>
>checkpatch reports a warning here.
>
>I think it should be like
>
Oh, thanks. I'll post fixed one, tomorrow.

Thanks,
-Kame

>@@ -2585,7 +2581,8 @@ static int __do_fault(struct mm_struct *mm, struct vm_a
rea_struct *vma,
> /* no need to invalidate: a not-present page won't be cached */
> update_mmu_cache(vma, address, entry);
> } else {
>- mem_cgroup_uncharge_page(page);
>+ if (charged)
>+ mem_cgroup_uncharge_page(page);
> if (anon)
> page_cache_release(page);
> else
>
>
>Thanks,
>Daisuke Nishimura.
>
>> Index: mmotm-2.6.27-rc7+/mm/rmap.c
>> ===================================================================
>> --- mmotm-2.6.27-rc7+.orig/mm/rmap.c
>> +++ mmotm-2.6.27-rc7+/mm/rmap.c
>> @@ -725,8 +725,8 @@ void page_remove_rmap(struct page *page,
>> page_clear_dirty(page);
>> set_page_dirty(page);
>> }
>> -
>> - mem_cgroup_uncharge_page(page);
>> + if (PageAnon(page))
>> + mem_cgroup_uncharge_page(page);
>> __dec_zone_page_state(page,
>> PageAnon(page) ? NR_ANON_PAGES : NR_FILE_MAPPED);
>> /*
>> Index: mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt
>> ===================================================================
>> --- mmotm-2.6.27-rc7+.orig/Documentation/controllers/memory.txt
>> +++ mmotm-2.6.27-rc7+/Documentation/controllers/memory.txt
>> @@ -112,14 +112,22 @@ the per cgroup LRU.
>>
>> 2.2.1 Accounting details
>>
>> -All mapped pages (RSS) and unmapped user pages (Page Cache) are accounted.
>> -RSS pages are accounted at the time of page_add_*_rmap() unless they've al
ready
>> -been accounted for earlier. A file page will be accounted for as Page Cach
e;
>> -it's mapped into the page tables of a process, duplicate accounting is car
efully
>> -avoided. Page Cache pages are accounted at the time of add_to_page_cache()
.
>> -The corresponding routines that remove a page from the page tables or remo
ves
>> -a page from Page Cache is used to decrement the accounting counters of the
>> -cgroup.
>> +All mapped anon pages (RSS) and cache pages (Page Cache) are accounted.
>> +(some pages which never be reclaimable and will not be on global LRU
>> + are not accounted. we just accounts pages under usual vm management.)
>> +
>> +RSS pages are accounted at page_fault unless they've already been accounte
d
>> +for earlier. A file page will be accounted for as Page Cache when it's
>> +inserted into inode (radix-tree). While it's mapped into the page tables o
f
>> +processes, duplicate accounting is carefully avoided.
>> +
>> +A RSS page is unaccounted when it's fully unmapped. A PageCache page is
>> +unaccounted when it's removed from radix-tree.
>> +
>> +At page migration, accounting information is kept.
>> +
>> +Note: we just account pages-on-lru because our purpose is to control amoun
t
>> +of used pages. not-on-lru pages are tend to be out-of-control from vm view
.
>>
>> 2.3 Shared Page Accounting
>>
>>



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