From: Wu Fengguang <fengguang.wu@intel.com>
To: KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Cc: Minchan Kim <minchan.kim@gmail.com>,
Huang Shijie <shijie8@gmail.com>,
"akpm@linux-foundation.org" <akpm@linux-foundation.org>,
"mel@csn.ul.ie" <mel@csn.ul.ie>,
"kosaki.motohiro@jp.fujitsu.com" <kosaki.motohiro@jp.fujitsu.com>,
"linux-mm@kvack.org" <linux-mm@kvack.org>,
Rik van Riel <riel@redhat.com>,
David Rientjes <rientjes@google.com>,
Christoph Lameter <cl@linux-foundation.org>,
Andrea Arcangeli <aarcange@redhat.com>
Subject: Re: [PATCH 4/4] mm/page_alloc : relieve zone->lock's pressure for memory free
Date: Tue, 12 Jan 2010 13:09:10 +0800 [thread overview]
Message-ID: <20100112050910.GA31136@localhost> (raw)
In-Reply-To: <20100112045906.GA30172@localhost>
[corrected CC to Christoph and Andrea]
On Tue, Jan 12, 2010 at 12:32:23PM +0800, KAMEZAWA Hiroyuki wrote:
> On Tue, 12 Jan 2010 12:21:16 +0800
> Wu Fengguang <fengguang.wu@intel.com> wrote:
> > > BTW,
> > > Hmm. It's not atomic as Kame pointed out.
> > >
> > > Now, zone->flags have several bit.
> > > * ZONE_ALL_UNRECLAIMALBE
> > > * ZONE_RECLAIM_LOCKED
> > > * ZONE_OOM_LOCKED.
> > >
> > > I think this flags are likely to race when the memory pressure is high.
> > > If we don't prevent race, concurrent reclaim and killing could be happened.
> > > So I think reset zone->flags outside of zone->lock would make our efforts which
> > > prevent current reclaim and killing invalidate.
> >
> > zone_set_flag()/zone_clear_flag() calls set_bit()/clear_bit() which is
> > atomic. Do you mean more high level exclusion?
> >
> Ah, sorry, I missed that.
> In my memory, this wasn't atomic ;) ...maybe recent change.
>
> I don't want to see atomic_ops here...So, how about making this back to be
> zone->all_unreclaimable word ?
>
> Clearing this is not necessary to be atomic because this is cleard at every
> page freeing.
Yes the cost is a bit high. This was introduced by David Rientjes
in commit e815af95f, let's hear opinions from him :)
Thanks,
Fengguang
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next prev parent reply other threads:[~2010-01-12 5:09 UTC|newest]
Thread overview: 41+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-11 4:37 [PATCH 1/4] mm/page_alloc : rename rmqueue_bulk to rmqueue_single Huang Shijie
2010-01-11 4:37 ` [PATCH 2/4] mm/page_alloc : relieve the zone->lock's pressure for allocation Huang Shijie
2010-01-11 4:37 ` [PATCH 3/4] mm/page_alloc : modify the return type of __free_one_page Huang Shijie
2010-01-11 4:37 ` [PATCH 4/4] mm/page_alloc : relieve zone->lock's pressure for memory free Huang Shijie
2010-01-11 5:20 ` Minchan Kim
2010-01-11 6:01 ` Huang Shijie
2010-01-11 6:27 ` Huang Shijie
2010-01-11 6:38 ` Minchan Kim
2010-01-11 6:59 ` Huang Shijie
2010-01-12 0:47 ` KAMEZAWA Hiroyuki
2010-01-12 2:02 ` Huang Shijie
2010-01-12 2:07 ` KAMEZAWA Hiroyuki
2010-01-12 2:32 ` Huang Shijie
2010-01-12 2:27 ` Wu Fengguang
2010-01-12 2:56 ` KOSAKI Motohiro
2010-01-12 3:02 ` Huang Shijie
2010-01-12 4:05 ` Minchan Kim
2010-01-12 4:21 ` Wu Fengguang
2010-01-12 4:32 ` KAMEZAWA Hiroyuki
2010-01-12 4:59 ` Wu Fengguang
2010-01-12 5:09 ` Wu Fengguang [this message]
2010-01-12 5:10 ` KOSAKI Motohiro
2010-01-12 7:36 ` David Rientjes
2010-01-12 8:56 ` KOSAKI Motohiro
2010-01-12 21:39 ` David Rientjes
2010-01-13 0:01 ` KOSAKI Motohiro
2010-01-12 4:48 ` Minchan Kim
2010-01-12 2:51 ` Huang Shijie
2010-01-12 3:03 ` Wu Fengguang
2010-01-12 3:05 ` KOSAKI Motohiro
2010-01-11 5:04 ` [PATCH 3/4] mm/page_alloc : modify the return type of __free_one_page Minchan Kim
2010-01-12 2:56 ` KOSAKI Motohiro
2010-01-18 11:25 ` Mel Gorman
2010-01-19 1:49 ` Huang Shijie
2010-01-11 5:02 ` [PATCH 2/4] mm/page_alloc : relieve the zone->lock's pressure for allocation Minchan Kim
2010-01-11 5:13 ` Huang Shijie
2010-01-12 2:54 ` KOSAKI Motohiro
2010-01-18 11:24 ` Mel Gorman
2010-01-11 5:00 ` [PATCH 1/4] mm/page_alloc : rename rmqueue_bulk to rmqueue_single Minchan Kim
2010-01-12 2:52 ` KOSAKI Motohiro
2010-01-18 11:21 ` Mel Gorman
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