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Date: Mon, 1 Aug 2011 00:24:01 +0900
From: Minchan Kim <minchan.kim@gmail.com>
To: Mel Gorman <mgorman@suse.de>
Cc: Peter Zijlstra <peterz@infradead.org>, Linux-MM <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>, XFS <xfs@oss.sgi.com>,
        Dave Chinner <david@fromorbit.com>,
        Christoph Hellwig <hch@infradead.org>,
        Johannes Weiner <jweiner@redhat.com>,
        Wu Fengguang <fengguang.wu@intel.com>, Jan Kara <jack@suse.cz>,
        Rik van Riel <riel@redhat.com>
Subject: Re: [PATCH 7/8] mm: vmscan: Immediately reclaim end-of-LRU dirty
 pages when writeback completes
Message-ID: <20110731152401.GE1735@barrios-desktop>
References: <1311265730-5324-1-git-send-email-mgorman@suse.de>
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 <1311339228.27400.34.camel@twins>
 <20110722132319.GX5349@suse.de>
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On Fri, Jul 22, 2011 at 02:23:19PM +0100, Mel Gorman wrote:
> On Fri, Jul 22, 2011 at 02:53:48PM +0200, Peter Zijlstra wrote:
> > On Thu, 2011-07-21 at 17:28 +0100, Mel Gorman wrote:
> > > When direct reclaim encounters a dirty page, it gets recycled around
> > > the LRU for another cycle. This patch marks the page PageReclaim
> > > similar to deactivate_page() so that the page gets reclaimed almost
> > > immediately after the page gets cleaned. This is to avoid reclaiming
> > > clean pages that are younger than a dirty page encountered at the
> > > end of the LRU that might have been something like a use-once page.
> > > 
> > 
> > > @@ -834,7 +834,15 @@ static unsigned long shrink_page_list(struct list_head *page_list,
> > >  			 */
> > >  			if (page_is_file_cache(page) &&
> > >  					(!current_is_kswapd() || priority >= DEF_PRIORITY - 2)) {
> > > -				inc_zone_page_state(page, NR_VMSCAN_WRITE_SKIP);
> > > +				/*
> > > +				 * Immediately reclaim when written back.
> > > +				 * Similar in principal to deactivate_page()
> > > +				 * except we already have the page isolated
> > > +				 * and know it's dirty
> > > +				 */
> > > +				inc_zone_page_state(page, NR_VMSCAN_INVALIDATE);
> > > +				SetPageReclaim(page);
> > > +
> > 
> > I find the invalidate name somewhat confusing. It makes me think we'll
> > drop the page without writeback, like invalidatepage().
> 
> I wasn't that happy with it either to be honest but didn't think of a
> better one at the time. nr_reclaim_deferred?

How about "NR_VMSCAN_IMMEDIATE_RECLAIM" like comment rotate_reclaimable_page?

> 
> -- 
> Mel Gorman
> SUSE Labs

-- 
Kind regards,
Minchan Kim