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Re: [PATCH 7/8] mm: vmscan: Immediately reclaim end-of-LRU dirty pages w

To: Mel Gorman <mgorman@xxxxxxx>
Subject: Re: [PATCH 7/8] mm: vmscan: Immediately reclaim end-of-LRU dirty pages when writeback completes
From: Peter Zijlstra <peterz@xxxxxxxxxxxxx>
Date: Fri, 22 Jul 2011 14:53:48 +0200
Cc: Linux-MM <linux-mm@xxxxxxxxx>, LKML <linux-kernel@xxxxxxxxxxxxxxx>, XFS <xfs@xxxxxxxxxxx>, Dave Chinner <david@xxxxxxxxxxxxx>, Christoph Hellwig <hch@xxxxxxxxxxxxx>, Johannes Weiner <jweiner@xxxxxxxxxx>, Wu Fengguang <fengguang.wu@xxxxxxxxx>, Jan Kara <jack@xxxxxxx>, Rik van Riel <riel@xxxxxxxxxx>, Minchan Kim <minchan.kim@xxxxxxxxx>
In-reply-to: <1311265730-5324-8-git-send-email-mgorman@xxxxxxx>
References: <1311265730-5324-1-git-send-email-mgorman@xxxxxxx> <1311265730-5324-8-git-send-email-mgorman@xxxxxxx>
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().

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