linux-kernel - Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim

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Message-ID: <20100706101235.GE13780@csn.ul.ie>
Date:	Tue, 6 Jul 2010 11:12:35 +0100
From:	Mel Gorman <mel@....ul.ie>
To:	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>
Cc:	Andrew Morton <akpm@...ux-foundation.org>,
	linux-kernel@...r.kernel.org, linux-fsdevel@...r.kernel.org,
	linux-mm@...ck.org, Dave Chinner <david@...morbit.com>,
	Chris Mason <chris.mason@...cle.com>,
	Nick Piggin <npiggin@...e.de>, Rik van Riel <riel@...hat.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Christoph Hellwig <hch@...radead.org>,
	KAMEZAWA Hiroyuki <kamezawa.hiroyu@...fujitsu.com>,
	Andrea Arcangeli <aarcange@...hat.com>
Subject: Re: [PATCH 12/14] vmscan: Do not writeback pages in direct reclaim

On Tue, Jul 06, 2010 at 09:36:41AM +0900, KOSAKI Motohiro wrote:
> Hello,
> 
> > Ok, that's reasonable as I'm still working on that patch. For example, the
> > patch disabled anonymous page writeback which is unnecessary as the stack
> > usage for anon writeback is less than file writeback. 
> 
> How do we examine swap-on-file?
> 

Anything in particular wrong with the following?

/*
 * For now, only kswapd can writeback filesystem pages as otherwise
 * there is a stack overflow risk
 */
static inline bool reclaim_can_writeback(struct scan_control *sc,
                                        struct page *page)
{
        return !page_is_file_cache(page) || current_is_kswapd();
}

Even if it is a swapfile, I didn't spot a case where the filesystems
writepage would be called. Did I miss something?

-- 
Mel Gorman
Part-time Phd Student                          Linux Technology Center
University of Limerick                         IBM Dublin Software Lab
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