From mboxrd@z Thu Jan  1 00:00:00 1970
Date: Thu, 8 Feb 2007 14:24:31 -0800
From: Andrew Morton <akpm@linux-foundation.org>
Subject: Re: Drop PageReclaim()
Message-Id: <20070208142431.eb81ae70.akpm@linux-foundation.org>
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To: Christoph Lameter <clameter@sgi.com>
Cc: Hugh Dickins <hugh@veritas.com>, linux-mm@kvack.org
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On Thu, 8 Feb 2007 14:14:39 -0800 (PST)
Christoph Lameter <clameter@sgi.com> wrote:

> On Thu, 8 Feb 2007, Andrew Morton wrote:
> 
> > During the vmscan we encounter a page at the tail of the inactive list
> > which we want to reclaim, but it's dirty.  So we start writeout and then
> > move it to the head of the inactive list and keep scanning.
> > 
> > When writeback completes, we take a look at the page to see if it still
> > seems to be reclaimable and if so, move it to the tail of the inactive list
> > so that it will be reclaimed very soon.
> 
> Still reclaimable means on the LRU and not activated?

See the tests in rotate_reclaimable_page():

	if (PageLocked(page))
		return 1;
	if (PageDirty(page))
		return 1;
	if (PageActive(page))
		return 1;
	if (!PageLRU(page))
		return 1;

> > PG_reclaim is used to indicate pages which need this treatment.
> 
> We have a mechanism to trigger events based on the end of writeback 
> (also triggered in end_page_writeback).

Not sure what you're referring to there.

> But I guess we are not using it 
> because we do not have a process context?

end_page_writeback() usually runs in hard IRQ context.

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