linux-kernel - Re: [PATCH 1/3] Rename pgmoved variable in shrink_active

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Message-Id: <20090717091920.A90C.A69D9226@jp.fujitsu.com>
Date:	Fri, 17 Jul 2009 14:43:37 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Johannes Weiner <hannes@...xchg.org>
Cc:	kosaki.motohiro@...fujitsu.com,
	LKML <linux-kernel@...r.kernel.org>,
	linux-mm <linux-mm@...ck.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Rik van Riel <riel@...hat.com>,
	Minchan Kim <minchan.kim@...il.com>,
	Christoph Lameter <cl@...ux-foundation.org>
Subject: Re: [PATCH 1/3] Rename pgmoved variable in shrink_active_list()

> On Thu, Jul 16, 2009 at 09:52:34AM +0900, KOSAKI Motohiro wrote:
> > Subject: [PATCH] Rename pgmoved variable in shrink_active_list()
> > 
> > Currently, pgmoved variable have two meanings. it cause harder reviewing a bit.
> > This patch separate it.
> > 
> > 
> > Signed-off-by: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> 
> Reviewed-by: Johannes Weiner <hannes@...xchg.org>
> 
> Below are just minor suggestions regarding the changed code.
> 
> > ---
> >  mm/vmscan.c |   16 ++++++++--------
> >  1 file changed, 8 insertions(+), 8 deletions(-)
> > 
> > Index: b/mm/vmscan.c
> > ===================================================================
> > --- a/mm/vmscan.c
> > +++ b/mm/vmscan.c
> > @@ -1239,7 +1239,7 @@ static void move_active_pages_to_lru(str
> >  static void shrink_active_list(unsigned long nr_pages, struct zone *zone,
> >  			struct scan_control *sc, int priority, int file)
> >  {
> > -	unsigned long pgmoved;
> > +	unsigned long nr_taken;
> >  	unsigned long pgscanned;
> >  	unsigned long vm_flags;
> >  	LIST_HEAD(l_hold);	/* The pages which were snipped off */
> > @@ -1247,10 +1247,11 @@ static void shrink_active_list(unsigned 
> >  	LIST_HEAD(l_inactive);
> >  	struct page *page;
> >  	struct zone_reclaim_stat *reclaim_stat = get_reclaim_stat(zone, sc);
> > +	unsigned long nr_rotated = 0;
> >  
> >  	lru_add_drain();
> >  	spin_lock_irq(&zone->lru_lock);
> > -	pgmoved = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
> > +	nr_taken = sc->isolate_pages(nr_pages, &l_hold, &pgscanned, sc->order,
> >  					ISOLATE_ACTIVE, zone,
> >  					sc->mem_cgroup, 1, file);
> >  	/*
> > @@ -1260,16 +1261,15 @@ static void shrink_active_list(unsigned 
> >  	if (scanning_global_lru(sc)) {
> >  		zone->pages_scanned += pgscanned;
> >  	}
> > -	reclaim_stat->recent_scanned[!!file] += pgmoved;
> > +	reclaim_stat->recent_scanned[!!file] += nr_taken;
> 
> Hm, file is a boolean already, the double negation can probably be
> dropped.
> 
> >  	__count_zone_vm_events(PGREFILL, zone, pgscanned);
> >  	if (file)
> > -		__mod_zone_page_state(zone, NR_ACTIVE_FILE, -pgmoved);
> > +		__mod_zone_page_state(zone, NR_ACTIVE_FILE, -nr_taken);
> >  	else
> > -		__mod_zone_page_state(zone, NR_ACTIVE_ANON, -pgmoved);
> > +		__mod_zone_page_state(zone, NR_ACTIVE_ANON, -nr_taken);
> 
> Should perhaps be in another patch, but we could use
> 
> 	__mod_zone_page_state(zone, LRU_ACTIVE + file * LRU_FILE);
> 
> like in the call to move_active_pages_to_lru().
>
> >  	spin_unlock_irq(&zone->lru_lock);
> >  
> > -	pgmoved = 0;  /* count referenced (mapping) mapped pages */
> >  	while (!list_empty(&l_hold)) {
> >  		cond_resched();
> >  		page = lru_to_page(&l_hold);
> > @@ -1283,7 +1283,7 @@ static void shrink_active_list(unsigned 
> >  		/* page_referenced clears PageReferenced */
> >  		if (page_mapping_inuse(page) &&
> >  		    page_referenced(page, 0, sc->mem_cgroup, &vm_flags)) {
> > -			pgmoved++;
> > +			nr_rotated++;
> >  			/*
> >  			 * Identify referenced, file-backed active pages and
> >  			 * give them one more trip around the active list. So
> > @@ -1312,7 +1312,7 @@ static void shrink_active_list(unsigned 
> >  	 * helps balance scan pressure between file and anonymous pages in
> >  	 * get_scan_ratio.
> >  	 */
> > -	reclaim_stat->recent_rotated[!!file] += pgmoved;
> > +	reclaim_stat->recent_rotated[!!file] += nr_rotated;
> 
> file is boolean.
> 
> There is one more double negation in isolate_pages_global() that can
> be dropped as well.  If you agree, I can submit all those changes in
> separate patches.

Yeah, thanks please. 



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