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From: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
To: Minchan Kim <minchan.kim@gmail.com>
Subject: Re: [PATCH v4 4/7] Reclaim invalidated page ASAP
Cc: kosaki.motohiro@jp.fujitsu.com, Andrew Morton <akpm@linux-foundation.org>,
        Rik van Riel <riel@redhat.com>, linux-mm <linux-mm@kvack.org>,
        LKML <linux-kernel@vger.kernel.org>,
        Wu Fengguang <fengguang.wu@intel.com>,
        Johannes Weiner <hannes@cmpxchg.org>, Nick Piggin <npiggin@kernel.dk>
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Date: Wed,  8 Dec 2010 17:04:34 +0900 (JST)
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> invalidate_mapping_pages is very big hint to reclaimer.
> It means user doesn't want to use the page any more.
> So in order to prevent working set page eviction, this patch
> move the page into tail of inactive list by PG_reclaim.
> 
> Please, remember that pages in inactive list are working set
> as well as active list. If we don't move pages into inactive list's
> tail, pages near by tail of inactive list can be evicted although
> we have a big clue about useless pages. It's totally bad.
> 
> Now PG_readahead/PG_reclaim is shared.
> fe3cba17 added ClearPageReclaim into clear_page_dirty_for_io for
> preventing fast reclaiming readahead marker page.
> 
> In this series, PG_reclaim is used by invalidated page, too.
> If VM find the page is invalidated and it's dirty, it sets PG_reclaim
> to reclaim asap. Then, when the dirty page will be writeback,
> clear_page_dirty_for_io will clear PG_reclaim unconditionally.
> It disturbs this serie's goal.
> 
> I think it's okay to clear PG_readahead when the page is dirty, not
> writeback time. So this patch moves ClearPageReadahead.
> 
> Signed-off-by: Minchan Kim <minchan.kim@gmail.com>
> Acked-by: Rik van Riel <riel@redhat.com>
> Acked-by: Mel Gorman <mel@csn.ul.ie>
> Cc: Wu Fengguang <fengguang.wu@intel.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
> Cc: Johannes Weiner <hannes@cmpxchg.org>
> Cc: Nick Piggin <npiggin@kernel.dk>

Until anyone should data, I will not ack this. This patch increase
VM state, but benefit is doubious.