From: Rik van Riel <riel@redhat.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH 2/3][v2] vmstat: add anon_scan_ratio field to zoneinfo
Date: Sun, 17 Jan 2010 21:16:06 -0500 [thread overview]
Message-ID: <4B53C466.4010103@redhat.com> (raw)
In-Reply-To: <28c262361001171810w544614b7rdd3df0f984692f35@mail.gmail.com>
On 01/17/2010 09:10 PM, Minchan Kim wrote:
> Absoultely right. I missed that. Thanks.
> get_scan_ratio used lru_lock to get reclaim_stat->recent_xxxx.
> But, it doesn't used lru_lock to get ap/fp.
>
> Is it intentional? I think you or Rik know it. :)
> I think if we want to get exact value, we have to use lru_lock until
> getting ap/fp.
> If it isn't, we don't need lru_lock when we get the reclaim_stat->recent_xxxx.
>
> What do you think about it?
This is definately not intentional.
Getting race conditions in this code could throw off the
statistics by a factor 2. I do not know how serious that
would be for the VM or whether (and how quickly) it would
self correct.
--
All rights reversed.
WARNING: multiple messages have this Message-ID (diff)
From: Rik van Riel <riel@redhat.com>
To: Minchan Kim <minchan.kim@gmail.com>
Cc: KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>,
LKML <linux-kernel@vger.kernel.org>,
linux-mm <linux-mm@kvack.org>,
Andrew Morton <akpm@linux-foundation.org>,
Balbir Singh <balbir@linux.vnet.ibm.com>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH 2/3][v2] vmstat: add anon_scan_ratio field to zoneinfo
Date: Sun, 17 Jan 2010 21:16:06 -0500 [thread overview]
Message-ID: <4B53C466.4010103@redhat.com> (raw)
In-Reply-To: <28c262361001171810w544614b7rdd3df0f984692f35@mail.gmail.com>
On 01/17/2010 09:10 PM, Minchan Kim wrote:
> Absoultely right. I missed that. Thanks.
> get_scan_ratio used lru_lock to get reclaim_stat->recent_xxxx.
> But, it doesn't used lru_lock to get ap/fp.
>
> Is it intentional? I think you or Rik know it. :)
> I think if we want to get exact value, we have to use lru_lock until
> getting ap/fp.
> If it isn't, we don't need lru_lock when we get the reclaim_stat->recent_xxxx.
>
> What do you think about it?
This is definately not intentional.
Getting race conditions in this code could throw off the
statistics by a factor 2. I do not know how serious that
would be for the VM or whether (and how quickly) it would
self correct.
--
All rights reversed.
--
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next prev parent reply other threads:[~2010-01-18 2:16 UTC|newest]
Thread overview: 38+ messages / expand[flat|nested] mbox.gz Atom feed top
2010-01-13 8:19 [PATCH 1/3] vmscan: get_scan_ratio cleanup KOSAKI Motohiro
2010-01-13 8:19 ` KOSAKI Motohiro
2010-01-13 8:21 ` [PATCH 2/3][v2] vmstat: add anon_scan_ratio field to zoneinfo KOSAKI Motohiro
2010-01-13 8:21 ` KOSAKI Motohiro
2010-01-13 10:31 ` Minchan Kim
2010-01-13 10:31 ` Minchan Kim
2010-01-13 23:50 ` KOSAKI Motohiro
2010-01-13 23:50 ` KOSAKI Motohiro
2010-01-14 5:12 ` Minchan Kim
2010-01-14 5:12 ` Minchan Kim
2010-01-14 5:18 ` KOSAKI Motohiro
2010-01-14 5:18 ` KOSAKI Motohiro
2010-01-15 17:23 ` Minchan Kim
2010-01-15 17:23 ` Minchan Kim
2010-01-18 1:04 ` KOSAKI Motohiro
2010-01-18 1:04 ` KOSAKI Motohiro
2010-01-18 1:47 ` Minchan Kim
2010-01-18 1:47 ` Minchan Kim
2010-01-18 1:54 ` KOSAKI Motohiro
2010-01-18 1:54 ` KOSAKI Motohiro
2010-01-18 2:10 ` Minchan Kim
2010-01-18 2:10 ` Minchan Kim
2010-01-18 2:14 ` KOSAKI Motohiro
2010-01-18 2:14 ` KOSAKI Motohiro
2010-01-18 2:16 ` Rik van Riel [this message]
2010-01-18 2:16 ` Rik van Riel
2010-01-18 2:24 ` KOSAKI Motohiro
2010-01-18 2:24 ` KOSAKI Motohiro
2010-01-18 2:25 ` Minchan Kim
2010-01-18 2:25 ` Minchan Kim
2010-01-13 8:22 ` [PATCH 3/3] [v2] memcg: add anon_scan_ratio to memory.stat file KOSAKI Motohiro
2010-01-13 8:22 ` KOSAKI Motohiro
2010-01-13 8:24 ` KAMEZAWA Hiroyuki
2010-01-13 8:24 ` KAMEZAWA Hiroyuki
2010-01-13 9:08 ` Balbir Singh
2010-01-13 9:08 ` Balbir Singh
2010-01-13 9:54 ` [PATCH 1/3] vmscan: get_scan_ratio cleanup Minchan Kim
2010-01-13 9:54 ` Minchan Kim
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