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Date: Mon, 20 Jul 2009 14:37:09 +0900 (JST)
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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Peter Zijlstra <peterz@infradead.org>
Subject: Re: [PATCH 4/5] Use add_page_to_lru_list() helper function
Cc: kosaki.motohiro@jp.fujitsu.com, LKML <linux-kernel@vger.kernel.org>,
       linux-mm <linux-mm@kvack.org>,
       Andrew Morton <akpm@linux-foundation.org>
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> > @@ -1241,7 +1241,6 @@ static void move_active_pages_to_lru(str
> >  			spin_lock_irq(&zone->lru_lock);
> >  		}
> >  	}
> > -	__mod_zone_page_state(zone, NR_LRU_BASE + lru, pgmoved);
> >  	if (!is_active_lru(lru))
> >  		__count_vm_events(PGDEACTIVATE, pgmoved);
> >  }
> 
> This is a net loss, you introduce pgmoved calls to __inc_zone_state,
> instead of the one __mod_zone_page_state() call.

max pgmoved is 32. 32 times __inc_zone_state() make 0 or 1 time
atomic operation (not much than two).
I don't think it reduce performance.