linux-kernel - Re: [PATCH 4/6] mm: kswapd: Reset kswapd_max_order and classzone

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Date:	Fri, 10 Dec 2010 10:42:54 +0000
From:	Mel Gorman <mel@....ul.ie>
To:	Minchan Kim <minchan.kim@...il.com>
Cc:	Simon Kirby <sim@...tway.ca>,
	KOSAKI Motohiro <kosaki.motohiro@...fujitsu.com>,
	Shaohua Li <shaohua.li@...el.com>,
	Dave Hansen <dave@...ux.vnet.ibm.com>,
	Johannes Weiner <hannes@...xchg.org>,
	Andrew Morton <akpm@...ux-foundation.org>,
	linux-mm <linux-mm@...ck.org>,
	linux-kernel <linux-kernel@...r.kernel.org>
Subject: Re: [PATCH 4/6] mm: kswapd: Reset kswapd_max_order and
	classzone_idx after reading

On Fri, Dec 10, 2010 at 01:03:01AM +0900, Minchan Kim wrote:
> On Fri, Dec 10, 2010 at 12:59 AM, Minchan Kim <minchan.kim@...il.com> wrote:
> > On Thu, Dec 09, 2010 at 11:18:18AM +0000, Mel Gorman wrote:
> >> When kswapd wakes up, it reads its order and classzone from pgdat and
> >> calls balance_pgdat. While its awake, it potentially reclaimes at a high
> >> order and a low classzone index. This might have been a once-off that
> >> was not required by subsequent callers. However, because the pgdat
> >> values were not reset, they remain artifically high while
> >> balance_pgdat() is running and potentially kswapd enters a second
> >> unnecessary reclaim cycle. Reset the pgdat order and classzone index
> >> after reading.
> >>
> >> Signed-off-by: Mel Gorman <mel@....ul.ie>
> > Reviewed-by: Minchan Kim <minchan.kim@...il.com>
> 
> Nitpick.
> Shouldn't this patch be merged with 1/6?
> 

I don't think so as it's a standalone fix. For example, if this was
merged on its own, the "order" should still be reset after reading.

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