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Date: Tue, 28 Feb 2012 10:25:44 +0400
From: Konstantin Khlebnikov <khlebnikov@...nvz.org>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
CC: Hugh Dickins <hughd@...gle.com>,
"linux-kernel@...r.kernel.org" <linux-kernel@...r.kernel.org>,
"linux-mm@...ck.org" <linux-mm@...ck.org>,
Johannes Weiner <hannes@...xchg.org>,
Andrew Morton <akpm@...ux-foundation.org>,
Andi Kleen <andi@...stfloor.org>
Subject: Re: [PATCH v3 15/21] mm: handle lruvec relocks on lumpy reclaim
KAMEZAWA Hiroyuki wrote:
> On Thu, 23 Feb 2012 17:52:52 +0400
> Konstantin Khlebnikov<khlebnikov@...nvz.org> wrote:
>
>> Prepare for lock splitting in lumly reclaim logic.
>> Now move_active_pages_to_lru() and putback_inactive_pages()
>> can put pages into different lruvecs.
>>
>> * relock book before SetPageLRU()
>
> lruvec ?
yeah, this came from v1
>
>> * update reclaim_stat pointer after relocks
>> * return currently locked lruvec
>>
>> Signed-off-by: Konstantin Khlebnikov<khlebnikov@...nvz.org>
>> ---
>> mm/vmscan.c | 45 +++++++++++++++++++++++++++++++++------------
>> 1 files changed, 33 insertions(+), 12 deletions(-)
>>
>> diff --git a/mm/vmscan.c b/mm/vmscan.c
>> index a3941d1..6eeeb4b 100644
>> --- a/mm/vmscan.c
>> +++ b/mm/vmscan.c
>> @@ -1114,6 +1114,7 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>> unsigned long *nr_scanned, struct scan_control *sc,
>> isolate_mode_t mode, int active, int file)
>> {
>> + struct lruvec *cursor_lruvec = lruvec;
>> struct list_head *src;
>> unsigned long nr_taken = 0;
>> unsigned long nr_lumpy_taken = 0;
>> @@ -1197,14 +1198,17 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>> !PageSwapCache(cursor_page))
>> break;
>>
>> + /* Switch cursor_lruvec lock for lumpy isolate */
>> + if (!__lock_page_lruvec_irq(&cursor_lruvec,
>> + cursor_page))
>> + continue;
>> +
>> if (__isolate_lru_page(cursor_page, mode, file) == 0) {
>> unsigned int isolated_pages;
>> - struct lruvec *cursor_lruvec;
>> int cursor_lru = page_lru(cursor_page);
>>
>> list_move(&cursor_page->lru, dst);
>> isolated_pages = hpage_nr_pages(cursor_page);
>> - cursor_lruvec = page_lruvec(cursor_page);
>> cursor_lruvec->pages_count[cursor_lru] -=
>> isolated_pages;
>> VM_BUG_ON((long)cursor_lruvec->
>> @@ -1235,6 +1239,9 @@ static unsigned long isolate_lru_pages(unsigned long nr_to_scan,
>> }
>> }
>>
>> + /* Restore original lruvec lock */
>> + cursor_lruvec = __relock_page_lruvec(cursor_lruvec, page);
>> +
>> /* If we break out of the loop above, lumpy reclaim failed */
>> if (pfn< end_pfn)
>> nr_lumpy_failed++;
>> @@ -1325,7 +1332,10 @@ static int too_many_isolated(struct zone *zone, int file,
>> return isolated> inactive;
>> }
>>
>> -static noinline_for_stack void
>> +/*
>> + * Returns currently locked lruvec
>> + */
>> +static noinline_for_stack struct lruvec *
>> putback_inactive_pages(struct lruvec *lruvec,
>> struct list_head *page_list)
>> {
>> @@ -1347,10 +1357,13 @@ putback_inactive_pages(struct lruvec *lruvec,
>> lock_lruvec_irq(lruvec);
>> continue;
>> }
>> +
>> + lruvec = __relock_page_lruvec(lruvec, page);
>> + reclaim_stat =&lruvec->reclaim_stat;
>> +
>> SetPageLRU(page);
>> lru = page_lru(page);
>>
>> - lruvec = page_lruvec(page);
>> add_page_to_lru_list(lruvec, page, lru);
>> if (is_active_lru(lru)) {
>> int file = is_file_lru(lru);
>> @@ -1375,6 +1388,8 @@ putback_inactive_pages(struct lruvec *lruvec,
>> * To save our caller's stack, now use input list for pages to free.
>> */
>> list_splice(&pages_to_free, page_list);
>> +
>> + return lruvec;
>> }
>>
>> static noinline_for_stack void
>> @@ -1544,7 +1559,7 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
>> __count_vm_events(KSWAPD_STEAL, nr_reclaimed);
>> __count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
>>
>> - putback_inactive_pages(lruvec,&page_list);
>> + lruvec = putback_inactive_pages(lruvec,&page_list);
>>
>> __mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
>> __mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
>> @@ -1603,12 +1618,15 @@ shrink_inactive_list(unsigned long nr_to_scan, struct lruvec *lruvec,
>> *
>> * The downside is that we have to touch page->_count against each page.
>> * But we had to alter page->flags anyway.
>> + *
>> + * Returns currently locked lruvec
>> */
>>
>> -static void move_active_pages_to_lru(struct lruvec *lruvec,
>> - struct list_head *list,
>> - struct list_head *pages_to_free,
>> - enum lru_list lru)
>> +static struct lruvec *
>> +move_active_pages_to_lru(struct lruvec *lruvec,
>> + struct list_head *list,
>> + struct list_head *pages_to_free,
>> + enum lru_list lru)
>> {
>> unsigned long pgmoved = 0;
>> struct page *page;
>> @@ -1630,10 +1648,11 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
>>
>> page = lru_to_page(list);
>>
>> + lruvec = __relock_page_lruvec(lruvec, page);
>> +
>> VM_BUG_ON(PageLRU(page));
>> SetPageLRU(page);
>>
>> - lruvec = page_lruvec(page);
>> list_move(&page->lru,&lruvec->pages_lru[lru]);
>> numpages = hpage_nr_pages(page);
>> lruvec->pages_count[lru] += numpages;
>> @@ -1655,6 +1674,8 @@ static void move_active_pages_to_lru(struct lruvec *lruvec,
>> __mod_zone_page_state(lruvec_zone(lruvec), NR_LRU_BASE + lru, pgmoved);
>> if (!is_active_lru(lru))
>> __count_vm_events(PGDEACTIVATE, pgmoved);
>> +
>> + return lruvec;
>> }
>>
>> static void shrink_active_list(unsigned long nr_to_scan,
>> @@ -1744,9 +1765,9 @@ static void shrink_active_list(unsigned long nr_to_scan,
>> */
>> reclaim_stat->recent_rotated[file] += nr_rotated;
>>
>> - move_active_pages_to_lru(lruvec,&l_active,&l_hold,
>> + lruvec = move_active_pages_to_lru(lruvec,&l_active,&l_hold,
>> LRU_ACTIVE + file * LRU_FILE);
>> - move_active_pages_to_lru(lruvec,&l_inactive,&l_hold,
>> + lruvec = move_active_pages_to_lru(lruvec,&l_inactive,&l_hold,
>> LRU_BASE + file * LRU_FILE);
>> __mod_zone_page_state(zone, NR_ISOLATED_ANON + file, -nr_taken);
>> unlock_lruvec_irq(lruvec);
>>
>
> Hmm...could you add comments to each function as
> "The caller should _lock_ lruvec before calling this functions.
> This function returns a lruvec with _locked_. It may be different from passed one.
> And The callser should unlock lruvec"
Ok. Documenting is not my best side =)
>
>
> Thanks,
> -Kame
>
>
>
>
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