From: Shaohua Li <shaohua.li@intel.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: linux-mm <linux-mm@kvack.org>, Andrew Morton <akpm@linux-foundation.org>
Subject: Re: [patch]vmscan: make kswapd use a correct order
Date: Wed, 01 Dec 2010 13:42:05 +0800 [thread overview]
Message-ID: <1291182125.12777.69.camel@sli10-conroe> (raw)
In-Reply-To: <AANLkTi=whw86_7T0tVi5S8xmwS+Z3PDE_AbXEJSQFqR4@mail.gmail.com>
On Wed, 2010-12-01 at 12:21 +0800, Minchan Kim wrote:
> On Wed, Dec 1, 2010 at 12:08 PM, Shaohua Li <shaohua.li@intel.com> wrote:
> > T0: Task1 wakeup_kswapd(order=3)
> > T1: kswapd enters balance_pgdat
> > T2: Task2 wakeup_kswapd(order=2), because pages reclaimed by kswapd are used
> > quickly
> > T3: kswapd exits balance_pgdat. kswapd will do check. Now new order=2,
> > pgdat->kswapd_max_order will become 0, but order=3, if sleeping_prematurely,
> > then order will become pgdat->kswapd_max_order(0), while at this time the
> > order should 2
> > This isn't a big deal, but we do have a small window the order is wrong.
> >
> > Signed-off-by: Shaohua Li <shaohua.li@intel.com>
> Reviewed-by: Minchan Kim <minchan.kim@gmai.com>
>
> But you need the description more easily.
>
> I try it.
Thanks, changed the description.
T0: Task 1 wakes up kswapd with order-3
T1: So, kswapd starts to reclaim pages using balance_pgdat
T2: Task 2 wakes up kswapd with order-2 because pages reclaimed by T1
are consumed quickly.
T3: kswapd exits balance_pgdat and will do following:
T4-1: In beginning of kswapd's loop, pgdat->kswapd_max_order will be
reset with zero.
T4-2: order will be set to pgdat->kswapd_max_order(0), since it enters the
false branch of 'if (order (3) < new_order (2))'
T4-3: If previous balance_pgdat can't meet requirement of order-2 free
pages by high watermark, it will start reclaiming again. So balance_pgdat will
use order-0 to do reclaim, while at this time it really should use order-2
This isn't a big deal, but we do have a small window the order is wrong.
Signed-off-by: Shaohua Li <shaohua.li@intel.com>
Reviewed-by: Minchan Kim <minchan.kim@gmail.com>
diff --git a/mm/vmscan.c b/mm/vmscan.c
index d31d7ce..c630349 100644
--- a/mm/vmscan.c
+++ b/mm/vmscan.c
@@ -2450,7 +2450,8 @@ static int kswapd(void *p)
}
}
- order = pgdat->kswapd_max_order;
+ order = max_t(unsigned long, new_order,
+ pgdat->kswapd_max_order);
}
finish_wait(&pgdat->kswapd_wait, &wait);
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next prev parent reply other threads:[~2010-12-01 5:42 UTC|newest]
Thread overview: 35+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-12-01 3:08 [patch]vmscan: make kswapd use a correct order Shaohua Li
2010-12-01 4:21 ` Minchan Kim
2010-12-01 5:42 ` Shaohua Li [this message]
2010-12-01 9:44 ` KOSAKI Motohiro
2010-12-01 15:58 ` Minchan Kim
2010-12-02 0:09 ` KOSAKI Motohiro
2010-12-02 0:29 ` KOSAKI Motohiro
2010-12-02 0:58 ` Minchan Kim
2010-12-02 0:19 ` Andrew Morton
2010-12-02 9:40 ` Mel Gorman
2010-12-02 0:29 ` Shaohua Li
2010-12-02 0:54 ` Minchan Kim
2010-12-02 1:05 ` Shaohua Li
2010-12-02 1:23 ` Minchan Kim
2010-12-02 1:36 ` Minchan Kim
2010-12-02 9:42 ` Mel Gorman
2010-12-02 15:25 ` Minchan Kim
2010-12-02 2:39 ` Shaohua Li
2010-12-02 1:28 ` KOSAKI Motohiro
2010-12-02 10:12 ` Mel Gorman
2010-12-02 15:35 ` Minchan Kim
2010-12-02 15:42 ` Mel Gorman
2010-12-02 20:53 ` Simon Kirby
2010-12-03 12:00 ` Mel Gorman
2010-12-04 12:07 ` Simon Kirby
2010-12-06 12:03 ` Mel Gorman
2010-12-09 23:44 ` Simon Kirby
2010-12-10 11:32 ` Mel Gorman
2010-12-10 23:42 ` Simon Kirby
2010-12-14 9:52 ` Mel Gorman
-- strict thread matches above, loose matches on Subject: below --
2010-12-02 16:00 [PATCH] vmscan: " Minchan Kim
2010-12-03 12:11 ` Mel Gorman
2010-12-09 22:13 ` Andrew Morton
2010-12-10 3:53 ` Minchan Kim
2010-12-10 11:17 ` Mel Gorman
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