linux-kernel - Re: [PATCH 2/2] mm: update_page_reclaim_stat() is called form page fault path

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Message-Id: <20090212103801.C8E1.KOSAKI.MOTOHIRO@jp.fujitsu.com>
Date:	Thu, 12 Feb 2009 10:38:44 +0900 (JST)
From:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
To:	Andrew Morton <akpm@...ux-foundation.org>
Cc:	kosaki.motohiro@...fujitsu.com, linux-kernel@...r.kernel.org,
	linux-mm@...ck.org, npiggin@...e.de, hugh@...itas.com,
	riel@...hat.com
Subject: Re: [PATCH 2/2] mm: update_page_reclaim_stat() is called form page fault path

> > +void update_page_reclaim_stat(struct page *page)
> > +{
> > +	struct zone *zone = page_zone(page);
> > +
> > +	spin_lock_irq(&zone->lru_lock);
> > +	/* if the page isn't reclaimable, it doesn't update reclaim stat */
> > +	if (PageLRU(page) && !PageUnevictable(page)) {
> > +		update_page_reclaim_stat_locked(zone, page,
> > +					 !!page_is_file_cache(page), 1);
> > +	}
> > +	spin_unlock_irq(&zone->lru_lock);
> > +}
> 
> And we just added a spin_lock_irq() and a bunch of other stuff to it.
> 
> Can we improve this?
> 
> Can we just omit it, even?
> 
> Can we update those stats locklessly and accomodate the resulting
> inaccuracy over at the codesites where these statistics are actually
> used?

fair enough.
thanks good suggestion.

I'm working it on.



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