From: Mel Gorman <mel@csn.ul.ie>
To: Christoph Lameter <cl@linux.com>
Cc: Andrew Morton <akpm@linux-foundation.org>,
Linux Kernel List <linux-kernel@vger.kernel.org>,
linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
Johannes Weiner <hannes@cmpxchg.org>,
Minchan Kim <minchan.kim@gmail.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake
Date: Thu, 2 Sep 2010 09:51:18 +0100 [thread overview]
Message-ID: <20100902085118.GA7670@csn.ul.ie> (raw)
In-Reply-To: <alpine.DEB.2.00.1009011942150.21189@router.home>
On Wed, Sep 01, 2010 at 07:43:41PM -0500, Christoph Lameter wrote:
> On Tue, 31 Aug 2010, Mel Gorman wrote:
>
> > +#ifdef CONFIG_SMP
> > +/* Called when a more accurate view of NR_FREE_PAGES is needed */
> > +unsigned long zone_nr_free_pages(struct zone *zone)
> > +{
> > + unsigned long nr_free_pages = zone_page_state(zone, NR_FREE_PAGES);
>
> You cannot call zone_page_state here because zone_page_state clips the
> counter at zero. The nr_free_pages needs to reflect the unclipped state
> and then the deltas need to be added. Then the clipping at zero can be
> done.
>
Good point. This justifies the use of a generic helper that is co-located
with vmstat.h. I've taken your zone_page_state_snapshot() patch, am using
the helper to take a more accurate reading of NR_FREE_PAGES and preparing
for a test. Thanks Christoph.
--
Mel Gorman
Part-time Phd Student Linux Technology Center
University of Limerick IBM Dublin Software Lab
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next prev parent reply other threads:[~2010-09-02 8:51 UTC|newest]
Thread overview: 65+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-08-31 17:37 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V3 Mel Gorman
2010-08-31 17:37 ` [PATCH 1/3] mm: page allocator: Update free page counters after pages are placed on the free list Mel Gorman
2010-08-31 18:17 ` Christoph Lameter
2010-09-01 7:10 ` Mel Gorman
2010-08-31 23:27 ` KOSAKI Motohiro
2010-08-31 17:37 ` [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake Mel Gorman
2010-08-31 18:20 ` Christoph Lameter
2010-08-31 23:37 ` KOSAKI Motohiro
2010-09-01 7:24 ` Mel Gorman
2010-09-01 7:33 ` KOSAKI Motohiro
2010-09-01 20:16 ` Christoph Lameter
2010-09-01 20:34 ` Mel Gorman
2010-09-02 0:24 ` Christoph Lameter
2010-09-02 0:26 ` KOSAKI Motohiro
2010-09-02 0:39 ` Christoph Lameter
2010-09-02 0:54 ` Christoph Lameter
2010-09-02 0:43 ` Christoph Lameter
2010-09-02 0:49 ` KOSAKI Motohiro
2010-09-02 8:51 ` Mel Gorman [this message]
2010-08-31 17:37 ` [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails Mel Gorman
2010-08-31 18:26 ` Christoph Lameter
-- strict thread matches above, loose matches on Subject: below --
2010-09-03 9:08 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V4 Mel Gorman
2010-09-03 9:08 ` [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake Mel Gorman
2010-09-03 22:55 ` Andrew Morton
2010-09-03 23:17 ` Christoph Lameter
2010-09-03 23:28 ` Andrew Morton
2010-09-04 0:54 ` Christoph Lameter
2010-09-05 18:12 ` Mel Gorman
2010-08-23 8:00 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V2 Mel Gorman
2010-08-23 8:00 ` [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake Mel Gorman
2010-08-23 12:56 ` Christoph Lameter
2010-08-23 13:03 ` Mel Gorman
2010-08-23 13:41 ` Christoph Lameter
2010-08-23 13:55 ` Mel Gorman
2010-08-23 16:04 ` Christoph Lameter
2010-08-23 16:13 ` Mel Gorman
2010-08-16 9:42 [RFC PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator Mel Gorman
2010-08-16 9:42 ` [PATCH 2/3] mm: page allocator: Calculate a better estimate of NR_FREE_PAGES when memory is low and kswapd is awake Mel Gorman
2010-08-16 9:43 ` Mel Gorman
2010-08-16 14:47 ` Rik van Riel
2010-08-16 16:06 ` Johannes Weiner
2010-08-17 2:26 ` Minchan Kim
2010-08-17 10:42 ` Mel Gorman
2010-08-17 15:01 ` Minchan Kim
2010-08-17 15:05 ` Mel Gorman
2010-08-17 10:16 ` Mel Gorman
2010-08-17 11:05 ` Johannes Weiner
2010-08-17 14:20 ` Minchan Kim
2010-08-18 8:51 ` Mel Gorman
2010-08-18 14:57 ` Minchan Kim
2010-08-19 8:06 ` Mel Gorman
2010-08-19 10:33 ` Minchan Kim
2010-08-19 10:38 ` Mel Gorman
2010-08-19 14:01 ` Minchan Kim
2010-08-19 14:09 ` Mel Gorman
2010-08-19 14:34 ` Minchan Kim
2010-08-19 15:07 ` Mel Gorman
2010-08-19 15:22 ` Minchan Kim
2010-08-19 15:40 ` Mel Gorman
2010-08-19 15:44 ` Minchan Kim
2010-08-19 15:46 ` Minchan Kim
2010-08-19 16:06 ` Mel Gorman
2010-08-19 16:45 ` Minchan Kim
2010-08-18 2:59 ` KAMEZAWA Hiroyuki
2010-08-18 15:55 ` Christoph Lameter
2010-08-19 0:07 ` KAMEZAWA Hiroyuki
2010-08-19 19:00 ` Christoph Lameter
2010-08-19 23:49 ` KAMEZAWA Hiroyuki
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