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Message-Id: <20091207144404.E947.A69D9226@jp.fujitsu.com>
Date:	Mon,  7 Dec 2009 14:48:08 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Wu Fengguang <fengguang.wu@...el.com>
Cc:	kosaki.motohiro@...fujitsu.com,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>
Subject: Re: [PATCH 1/4] vmscan: more simplify shrink_inactive_list()

> Hi KOSAKI,
> 
> It would be easier to review if you can split the changes and the big
> "unshift" :)

Umm. I don't like break checkpatch.pl rule ;)
if you have enough time, can you please use diff -b yourself?


> Otherwise it looks good to me. (actually I've advocated it before ;)
> 
> Thanks,
> Fengguang
> 
> On Fri, Nov 27, 2009 at 09:17:48AM +0900, KOSAKI Motohiro wrote:
> > This patch depend on "vmscan : simplify code" patch (written by Huang Shijie)
> > 
> > =========================================
> > Now, max_scan of shrink_inactive_list() is always passed less than
> > SWAP_CLUSTER_MAX. then, we can remove scanning pages loop in it.
> > 
> > detail
> >  - remove "while (nr_scanned < max_scan)" loop
> >  - remove nr_freed variable (now, we use nr_reclaimed directly)
> >  - remove nr_scan variable (now, we use nr_scanned directly)
> >  - rename max_scan to nr_to_scan
> >  - pass nr_to_scan into isolate_pages() directly instead
> >    using SWAP_CLUSTER_MAX
> > 
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> > ---
> >  mm/vmscan.c |  194 ++++++++++++++++++++++++++++-------------------------------
> >  1 files changed, 91 insertions(+), 103 deletions(-)
> > 
> > diff --git a/mm/vmscan.c b/mm/vmscan.c
> > index 7536991..a58ff15 100644
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1085,16 +1085,22 @@ static int too_many_isolated(struct zone *zone, int file,
> >   * shrink_inactive_list() is a helper for shrink_zone().  It returns the number
> >   * of reclaimed pages
> >   */
> > -static unsigned long shrink_inactive_list(unsigned long max_scan,
> > -			struct zone *zone, struct scan_control *sc,
> > -			int priority, int file)
> > +static unsigned long shrink_inactive_list(unsigned long nr_to_scan,
> > +					  struct zone *zone, struct scan_control *sc,
> > +					  int priority, int file)
> >  {
> >  	LIST_HEAD(page_list);
> >  	struct pagevec pvec;
> > -	unsigned long nr_scanned = 0;
> > +	unsigned long nr_scanned;
> >  	unsigned long nr_reclaimed = 0;
> >  	struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> >  	int lumpy_reclaim = 0;
> > +	struct page *page;
> > +	unsigned long nr_taken;
> > +	unsigned long nr_active;
> > +	unsigned int count[NR_LRU_LISTS] = { 0, };
> > +	unsigned long nr_anon;
> > +	unsigned long nr_file;
> >  
> >  	while (unlikely(too_many_isolated(zone, file, sc))) {
> >  		congestion_wait(BLK_RW_ASYNC, HZ/10);
> > @@ -1120,119 +1126,101 @@ static unsigned long shrink_inactive_list(unsigned long max_scan,
> >  
> >  	lru_add_drain();
> >  	spin_lock_irq(&zone->lru_lock);
> > -	do {
> > -		struct page *page;
> > -		unsigned long nr_taken;
> > -		unsigned long nr_scan;
> > -		unsigned long nr_freed;
> > -		unsigned long nr_active;
> > -		unsigned int count[NR_LRU_LISTS] = { 0, };
> > -		int mode = lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE;
> > -		unsigned long nr_anon;
> > -		unsigned long nr_file;
> > -
> > -		nr_taken = sc->isolate_pages(SWAP_CLUSTER_MAX,
> > -			     &page_list, &nr_scan, sc->order, mode,
> > -				zone, sc->mem_cgroup, 0, file);
> > +	nr_taken = sc->isolate_pages(nr_to_scan,
> > +				     &page_list, &nr_scanned, sc->order,
> > +				     lumpy_reclaim ? ISOLATE_BOTH : ISOLATE_INACTIVE,
> > +				     zone, sc->mem_cgroup, 0, file);
> >  
> > -		if (scanning_global_lru(sc)) {
> > -			zone->pages_scanned += nr_scan;
> > -			if (current_is_kswapd())
> > -				__count_zone_vm_events(PGSCAN_KSWAPD, zone,
> > -						       nr_scan);
> > -			else
> > -				__count_zone_vm_events(PGSCAN_DIRECT, zone,
> > -						       nr_scan);
> > -		}
> > +	if (scanning_global_lru(sc)) {
> > +		zone->pages_scanned += nr_scanned;
> > +		if (current_is_kswapd())
> > +			__count_zone_vm_events(PGSCAN_KSWAPD, zone, nr_scanned);
> > +		else
> > +			__count_zone_vm_events(PGSCAN_DIRECT, zone, nr_scanned);
> > +	}
> >  
> > -		if (nr_taken == 0)
> > -			goto done;
> > +	if (nr_taken == 0)
> > +		goto done;
> >  
> > -		nr_active = clear_active_flags(&page_list, count);
> > -		__count_vm_events(PGDEACTIVATE, nr_active);
> > +	nr_active = clear_active_flags(&page_list, count);
> > +	__count_vm_events(PGDEACTIVATE, nr_active);
> >  
> > -		__mod_zone_page_state(zone, NR_ACTIVE_FILE,
> > -						-count[LRU_ACTIVE_FILE]);
> > -		__mod_zone_page_state(zone, NR_INACTIVE_FILE,
> > -						-count[LRU_INACTIVE_FILE]);
> > -		__mod_zone_page_state(zone, NR_ACTIVE_ANON,
> > -						-count[LRU_ACTIVE_ANON]);
> > -		__mod_zone_page_state(zone, NR_INACTIVE_ANON,
> > -						-count[LRU_INACTIVE_ANON]);
> > +	__mod_zone_page_state(zone, NR_ACTIVE_FILE,
> > +			      -count[LRU_ACTIVE_FILE]);
> > +	__mod_zone_page_state(zone, NR_INACTIVE_FILE,
> > +			      -count[LRU_INACTIVE_FILE]);
> > +	__mod_zone_page_state(zone, NR_ACTIVE_ANON,
> > +			      -count[LRU_ACTIVE_ANON]);
> > +	__mod_zone_page_state(zone, NR_INACTIVE_ANON,
> > +			      -count[LRU_INACTIVE_ANON]);
> >  
> > -		nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
> > -		nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
> > -		__mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
> > -		__mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
> > +	nr_anon = count[LRU_ACTIVE_ANON] + count[LRU_INACTIVE_ANON];
> > +	nr_file = count[LRU_ACTIVE_FILE] + count[LRU_INACTIVE_FILE];
> > +	__mod_zone_page_state(zone, NR_ISOLATED_ANON, nr_anon);
> > +	__mod_zone_page_state(zone, NR_ISOLATED_FILE, nr_file);
> >  
> > -		reclaim_stat->recent_scanned[0] += nr_anon;
> > -		reclaim_stat->recent_scanned[1] += nr_file;
> > +	reclaim_stat->recent_scanned[0] += nr_anon;
> > +	reclaim_stat->recent_scanned[1] += nr_file;
> >  
> > -		spin_unlock_irq(&zone->lru_lock);
> > +	spin_unlock_irq(&zone->lru_lock);
> >  
> > -		nr_scanned += nr_scan;
> > -		nr_freed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
> > +	nr_reclaimed = shrink_page_list(&page_list, sc, PAGEOUT_IO_ASYNC);
> > +
> > +	/*
> > +	 * If we are direct reclaiming for contiguous pages and we do
> > +	 * not reclaim everything in the list, try again and wait
> > +	 * for IO to complete. This will stall high-order allocations
> > +	 * but that should be acceptable to the caller
> > +	 */
> > +	if (nr_reclaimed < nr_taken && !current_is_kswapd() && lumpy_reclaim) {
> > +		congestion_wait(BLK_RW_ASYNC, HZ/10);
> >  
> >  		/*
> > -		 * If we are direct reclaiming for contiguous pages and we do
> > -		 * not reclaim everything in the list, try again and wait
> > -		 * for IO to complete. This will stall high-order allocations
> > -		 * but that should be acceptable to the caller
> > +		 * The attempt at page out may have made some
> > +		 * of the pages active, mark them inactive again.
> >  		 */
> > -		if (nr_freed < nr_taken && !current_is_kswapd() &&
> > -		    lumpy_reclaim) {
> > -			congestion_wait(BLK_RW_ASYNC, HZ/10);
> > -
> > -			/*
> > -			 * The attempt at page out may have made some
> > -			 * of the pages active, mark them inactive again.
> > -			 */
> > -			nr_active = clear_active_flags(&page_list, count);
> > -			count_vm_events(PGDEACTIVATE, nr_active);
> > -
> > -			nr_freed += shrink_page_list(&page_list, sc,
> > -							PAGEOUT_IO_SYNC);
> > -		}
> > +		nr_active = clear_active_flags(&page_list, count);
> > +		count_vm_events(PGDEACTIVATE, nr_active);
> >  
> > -		nr_reclaimed += nr_freed;
> > +		nr_reclaimed += shrink_page_list(&page_list, sc,
> > +						 PAGEOUT_IO_SYNC);
> > +	}
> >  
> > -		local_irq_disable();
> > -		if (current_is_kswapd())
> > -			__count_vm_events(KSWAPD_STEAL, nr_freed);
> > -		__count_zone_vm_events(PGSTEAL, zone, nr_freed);
> > +	local_irq_disable();
> > +	if (current_is_kswapd())
> > +		__count_vm_events(KSWAPD_STEAL, nr_reclaimed);
> > +	__count_zone_vm_events(PGSTEAL, zone, nr_reclaimed);
> >  
> > -		spin_lock(&zone->lru_lock);
> > -		/*
> > -		 * Put back any unfreeable pages.
> > -		 */
> > -		while (!list_empty(&page_list)) {
> > -			int lru;
> > -			page = lru_to_page(&page_list);
> > -			VM_BUG_ON(PageLRU(page));
> > -			list_del(&page->lru);
> > -			if (unlikely(!page_evictable(page, NULL))) {
> > -				spin_unlock_irq(&zone->lru_lock);
> > -				putback_lru_page(page);
> > -				spin_lock_irq(&zone->lru_lock);
> > -				continue;
> > -			}
> > -			SetPageLRU(page);
> > -			lru = page_lru(page);
> > -			add_page_to_lru_list(zone, page, lru);
> > -			if (is_active_lru(lru)) {
> > -				int file = is_file_lru(lru);
> > -				reclaim_stat->recent_rotated[file]++;
> > -			}
> > -			if (!pagevec_add(&pvec, page)) {
> > -				spin_unlock_irq(&zone->lru_lock);
> > -				__pagevec_release(&pvec);
> > -				spin_lock_irq(&zone->lru_lock);
> > -			}
> > +	spin_lock(&zone->lru_lock);
> > +	/*
> > +	 * Put back any unfreeable pages.
> > +	 */
> > +	while (!list_empty(&page_list)) {
> > +		int lru;
> > +		page = lru_to_page(&page_list);
> > +		VM_BUG_ON(PageLRU(page));
> > +		list_del(&page->lru);
> > +		if (unlikely(!page_evictable(page, NULL))) {
> > +			spin_unlock_irq(&zone->lru_lock);
> > +			putback_lru_page(page);
> > +			spin_lock_irq(&zone->lru_lock);
> > +			continue;
> >  		}
> > -		__mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> > -		__mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> > -
> > -  	} while (nr_scanned < max_scan);
> > +		SetPageLRU(page);
> > +		lru = page_lru(page);
> > +		add_page_to_lru_list(zone, page, lru);
> > +		if (is_active_lru(lru)) {
> > +			int file = is_file_lru(lru);
> > +			reclaim_stat->recent_rotated[file]++;
> > +		}
> > +		if (!pagevec_add(&pvec, page)) {
> > +			spin_unlock_irq(&zone->lru_lock);
> > +			__pagevec_release(&pvec);
> > +			spin_lock_irq(&zone->lru_lock);
> > +		}
> > +	}
> > +	__mod_zone_page_state(zone, NR_ISOLATED_ANON, -nr_anon);
> > +	__mod_zone_page_state(zone, NR_ISOLATED_FILE, -nr_file);
> >  
> >  done:
> >  	spin_unlock_irq(&zone->lru_lock);
> > -- 
> > 1.6.5.2
> > 
> > 
> > 
> > --
> > To unsubscribe, send a message with 'unsubscribe linux-mm' in
> > the body to majordomo@...ck.org.  For more info on Linux MM,
> > see: http://www.linux-mm.org/ .
> > Don't email: <a href=mailto:"dont@...ck.org"> email@...ck.org </a>



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