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Message-Id: <20090115212030.EBE9.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date: Thu, 15 Jan 2009 22:34:27 +0900 (JST)
From: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To: Hugh Dickins <hugh@...itas.com>
Cc: kosaki.motohiro@...fujitsu.com,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
balbir@...ux.vnet.ibm.com,
Daisuke Nishimura <nishimura@....nes.nec.co.jp>,
linux-mm@...ck.org, linux-kernel@...r.kernel.org,
lizf@...fujitsu.com, menage@...gle.com,
Nick Piggin <npiggin@...e.de>, Rik van Riel <riel@...hat.com>
Subject: Re: [PATCH] mark_page_accessed() in do_swap_page() move latter than memcg charge
(CC to Rik and Nick)
Hi
Thank you reviewing.
> > mark_page_accessed() update reclaim_stat statics.
> > but currently, memcg charge is called after mark_page_accessed().
> >
> > then, mark_page_accessed() don't update memcg statics correctly.
>
> Statics? "Stats" is a good abbreviation for statistics,
> but statics are something else.
Doh! your are definitly right. thanks.
> > ---
> > mm/memory.c | 4 ++--
> > 1 file changed, 2 insertions(+), 2 deletions(-)
> >
> > Index: b/mm/memory.c
> > ===================================================================
> > --- a/mm/memory.c
> > +++ b/mm/memory.c
> > @@ -2426,8 +2426,6 @@ static int do_swap_page(struct mm_struct
> > count_vm_event(PGMAJFAULT);
> > }
> >
> > - mark_page_accessed(page);
> > -
> > lock_page(page);
> > delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
> >
> > @@ -2480,6 +2478,8 @@ static int do_swap_page(struct mm_struct
> > try_to_free_swap(page);
> > unlock_page(page);
> >
> > + mark_page_accessed(page);
> > +
> > if (write_access) {
> > ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
> > if (ret & VM_FAULT_ERROR)
>
> This catches my eye, because I'd discussed with Nick and was going to
> send in a patch which entirely _removes_ this mark_page_accessed call
> from do_swap_page (and replaces follow_page's mark_page_accessed call
> by a pte_mkyoung): they seem inconsistent to me, in the light of
> bf3f3bc5e734706730c12a323f9b2068052aa1f0 mm: don't mark_page_accessed
> in fault path.
Actually, bf3f3bc5e734706730c12a323f9b2068052aa1f0 only remove
the mark_page_accessed() in filemap_fault().
current mmotm's do_swap_page() still have mark_page_accessed().
but your suggestion is very worth.
ok, I'm thinking and sorting out again.
Rik's commit 9ff473b9a72942c5ac0ad35607cae28d8d59ed7a vmscan: evict streaming IO first
does "reclaim stastics don't only update at reclaim, but also at fault and read/write.
it makes proper anon/file reclaim balancing stastics value before starting actual reclaim".
and it depend on fault path calling mark_page_accessed().
Then, we need following change. I think.
- Remove calling mark_page_accessed() in do_swap_page().
it makes consistency against filemap_fault().
- Add calling update_page_reclaim_stat() into do_swap_page() and
filemap_fault().
Am I overlooking something?
> Though I need to give it another think through first: the situation
> is muddied by the way we (rightly) don't bother to do the mark_page_
> accessed on Anon in zap_pte_range anyway; and anon/swap has an
> independent lifecycle now with the separate swapbacked LRUs.
>
> What do you think? I didn't look further into your memcg situation,
> and what this patch is about: I'm unclear whether my patch to remove
> that mark_page_accessed would solve your problem, or mess you up.
===========================
Subject: [PATCH] mm: solve reclaim statistics confliction
commit 9ff473b9a72942c5ac0ad35607cae28d8d59ed7a "vmscan: evict streaming IO first"
require to update reclaim statistics in page fault and depend on that fault path call
mark_page_accessed().
but commit bf3f3bc5e734706730c12a323f9b2068052aa1f0 "mm: don't mark_page_accessed
in fault path." require to remove mark_page_accessed() from fault path.
They have conflict requirement.
the solusion is,
- Remove calling mark_page_accessed() in do_swap_page().
it makes consistency against filemap_fault().
- Add calling update_page_reclaim_stat() into do_swap_page() and
filemap_fault().
Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
Cc: Daisuke Nishimura <nishimura@....nes.nec.co.jp>
Cc: Balbir Singh <balbir@...ux.vnet.ibm.com>
Cc: Nick Piggin <npiggin@...e.de>
Cc: Rik van Riel <riel@...hat.com>
---
include/linux/swap.h | 2 ++
mm/filemap.c | 1 +
mm/memory.c | 4 ++--
mm/swap.c | 4 ++--
4 files changed, 7 insertions(+), 4 deletions(-)
Index: b/include/linux/swap.h
===================================================================
--- a/include/linux/swap.h
+++ b/include/linux/swap.h
@@ -185,6 +185,8 @@ extern void rotate_reclaimable_page(stru
extern void swap_setup(void);
extern void add_page_to_unevictable_list(struct page *page);
+extern void update_page_reclaim_stat(struct zone *zone, struct page *page,
+ int file, int rotated);
/**
* lru_cache_add: add a page to the page lists
Index: b/mm/filemap.c
===================================================================
--- a/mm/filemap.c
+++ b/mm/filemap.c
@@ -1637,6 +1637,7 @@ retry_page_update:
/*
* Found the page and have a reference on it.
*/
+ update_page_reclaim_stat(page_zone(page), page, 1, 1);
ra->prev_pos = (loff_t)page->index << PAGE_CACHE_SHIFT;
vmf->page = page;
return ret | VM_FAULT_LOCKED;
Index: b/mm/memory.c
===================================================================
--- a/mm/memory.c
+++ b/mm/memory.c
@@ -2426,8 +2426,6 @@ static int do_swap_page(struct mm_struct
count_vm_event(PGMAJFAULT);
}
- mark_page_accessed(page);
-
lock_page(page);
delayacct_clear_flag(DELAYACCT_PF_SWAPIN);
@@ -2480,6 +2478,8 @@ static int do_swap_page(struct mm_struct
try_to_free_swap(page);
unlock_page(page);
+ update_page_reclaim_stat(page_zone(page), page, 0, 1);
+
if (write_access) {
ret |= do_wp_page(mm, vma, address, page_table, pmd, ptl, pte);
if (ret & VM_FAULT_ERROR)
Index: b/mm/swap.c
===================================================================
--- a/mm/swap.c
+++ b/mm/swap.c
@@ -151,8 +151,8 @@ void rotate_reclaimable_page(struct pag
}
}
-static void update_page_reclaim_stat(struct zone *zone, struct page *page,
- int file, int rotated)
+void update_page_reclaim_stat(struct zone *zone, struct page *page,
+ int file, int rotated)
{
struct zone_reclaim_stat *reclaim_stat = &zone->reclaim_stat;
struct zone_reclaim_stat *memcg_reclaim_stat;
--
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