From: Minchan Kim <minchan.kim@gmail.com>
To: Mel Gorman <mel@csn.ul.ie>
Cc: linux-mm@kvack.org, Rik van Riel <riel@redhat.com>,
Nick Piggin <npiggin@suse.de>,
Johannes Weiner <hannes@cmpxchg.org>,
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: Fri, 20 Aug 2010 01:45:34 +0900 [thread overview]
Message-ID: <20100819164534.GB1345@barrios-desktop> (raw)
In-Reply-To: <20100819160612.GF19797@csn.ul.ie>
On Thu, Aug 19, 2010 at 05:06:12PM +0100, Mel Gorman wrote:
> On Fri, Aug 20, 2010 at 12:46:38AM +0900, Minchan Kim wrote:
> Mel. Could you consider normal(or small) system but has two core at least?
>
> I did consider it but I was not keen on the idea of small systems behaving
> very differently to large systems in this regard. I thought there was a
> danger that a problem problem would be hidden by such a move.
>
> > I means we apply you rule according to the number of CPU and RAM size. (ie,
> > threshold value).
> > Now mobile system begin to have two core in system and above 1G RAM.
> > Such case, it has threshold 8.
> >
> > It is unlikey to happen livelock.
> > Is it worth to have such overhead in such system?
> > What do you think?
> >
>
> Such overhead could be avoided if we made a check like the following in
> refresh_zone_stat_thresholds()
>
> /*
> * Only set percpu_drift_mark if there is a danger that
> * NR_FREE_PAGES reports the low watermark is ok when in fact
> * the min watermark could be breached by an allocation
> */
> tolerate_drift = low_wmark_pages(zone) - min_wmark_pages(zone);
> max_drift = num_online_cpus() * threshold;
> if (max_drift > tolerate_drift)
> zone->percpu_drift_mark = high_wmark_pages(zone)
> + max_drift;
>
> Would this be preferable?
Yes. It looks good to me.
>
> --
> Mel Gorman
> Part-time Phd Student Linux Technology Center
> University of Limerick IBM Dublin Software Lab
--
Kind regards,
Minchan Kim
--
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next prev parent reply other threads:[~2010-08-19 16:45 UTC|newest]
Thread overview: 76+ messages / expand[flat|nested] mbox.gz Atom feed top
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 1/3] mm: page allocator: Update free page counters after pages are placed on the free list Mel Gorman
2010-08-16 14:04 ` Rik van Riel
2010-08-16 15:26 ` Johannes Weiner
2010-08-17 2:21 ` Minchan Kim
2010-08-17 9:59 ` Mel Gorman
2010-08-17 14:25 ` Minchan Kim
2010-08-18 2:21 ` KAMEZAWA Hiroyuki
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 [this message]
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
2010-08-20 0:22 ` [PATCH] vmstat : update zone stat threshold at onlining a cpu KAMEZAWA Hiroyuki
2010-08-20 14:54 ` Christoph Lameter
2010-08-20 17:29 ` Andrew Morton
2010-08-23 7:18 ` Mel Gorman
2010-08-16 9:42 ` [PATCH 3/3] mm: page allocator: Drain per-cpu lists after direct reclaim allocation fails Mel Gorman
2010-08-16 14:50 ` Rik van Riel
2010-08-17 2:57 ` Minchan Kim
2010-08-18 3:02 ` KAMEZAWA Hiroyuki
2010-08-19 14:47 ` Minchan Kim
2010-08-19 15:10 ` 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
2010-08-31 17:37 [PATCH 0/3] Reduce watermark-related problems with the per-cpu allocator V3 Mel Gorman
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
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
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