linux-kernel - Re: [PATCH v5 3/4] Reclaim invalidated page ASAP

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Date:	Fri, 18 Feb 2011 01:06:03 +0900
From:	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	LKML <linux-kernel@...r.kernel.org>,
	Steven Barrett <damentz@...uorix.net>,
	Ben Gamari <bgamari.foss@...il.com>,
	Peter Zijlstra <peterz@...radead.org>,
	Rik van Riel <riel@...hat.com>, Mel Gorman <mel@....ul.ie>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Wu Fengguang <fengguang.wu@...el.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Nick Piggin <npiggin@...nel.dk>,
	Andrea Arcangeli <aarcange@...hat.com>,
	Balbir Singh <balbir@...ux.vnet.ibm.com>
Subject: Re: [PATCH v5 3/4] Reclaim invalidated page ASAP

On Fri, 18 Feb 2011 00:08:21 +0900
Minchan Kim <minchan.kim@...il.com> wrote:

> 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.
> In v4, ClearPageReadahead in set_page_dirty has a problem which is reported
> by Steven Barrett. It's due to compound page. Some driver(ex, audio) calls 
> set_page_dirty with compound page which isn't on LRU. but my patch does 
> ClearPageRelcaim on compound page. In non-CONFIG_PAGEFLAGS_EXTENDED, it breaks
> PageTail flag.
> 
> I think it doesn't affect THP and pass my test with THP enabling 
> but Cced Andrea for double check.
> 
> Reported-by: Steven Barrett <damentz@...uorix.net>
> Reviewed-by: Johannes Weiner <hannes@...xchg.org>
> Acked-by: Rik van Riel <riel@...hat.com>
> Acked-by: Mel Gorman <mel@....ul.ie>
> Cc: Wu Fengguang <fengguang.wu@...el.com>
> Cc: KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
> Cc: Nick Piggin <npiggin@...nel.dk>
> Cc: Andrea Arcangeli <aarcange@...hat.com>
> Signed-off-by: Minchan Kim <minchan.kim@...il.com>

Reviewed-by: KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>

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