From: Konstantin Khlebnikov <khlebnikov@openvz.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Johannes Weiner <jweiner@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH resend] mm: drain percpu lru add/rotate page-vectors on cpu hot-unplug
Date: Thu, 01 Mar 2012 12:06:46 +0400 [thread overview]
Message-ID: <4F4F2E16.5080703@openvz.org> (raw)
In-Reply-To: <20120229123818.61a61e9d.akpm@linux-foundation.org>
Andrew Morton wrote:
> On Tue, 28 Feb 2012 23:40:45 +0400
> Konstantin Khlebnikov<khlebnikov@openvz.org> wrote:
>
>> This cpu hotplug hook was accidentally removed in commit v2.6.30-rc4-18-g00a62ce
>> ("mm: fix Committed_AS underflow on large NR_CPUS environment")
>
> That was a long time ago - maybe we should leave it removed ;) I mean,
> did this bug(?) have any visible effect? If so, what was that effect?
It's because cpu hotplug/unplug isn't widely used feature.
Visible effect -- some pages are borrowed in per-cpu page-vectors.
Truncate can deal with it, but these pages cannot be reused while this cpu is offline.
So this is like temporary memory leak.
>
> IOW, the changelog didn't give anyone any reason to apply the patch to
> anything!
Sorry, I'm just stuck in pile of patches. It seems I should stop and send them one by one.
This one isn't critical, so there no reasons for pushing it into stable branches.
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WARNING: multiple messages have this Message-ID (diff)
From: Konstantin Khlebnikov <khlebnikov@openvz.org>
To: Andrew Morton <akpm@linux-foundation.org>
Cc: "linux-mm@kvack.org" <linux-mm@kvack.org>,
"linux-kernel@vger.kernel.org" <linux-kernel@vger.kernel.org>,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>,
Johannes Weiner <jweiner@redhat.com>,
KOSAKI Motohiro <kosaki.motohiro@jp.fujitsu.com>
Subject: Re: [PATCH resend] mm: drain percpu lru add/rotate page-vectors on cpu hot-unplug
Date: Thu, 01 Mar 2012 12:06:46 +0400 [thread overview]
Message-ID: <4F4F2E16.5080703@openvz.org> (raw)
In-Reply-To: <20120229123818.61a61e9d.akpm@linux-foundation.org>
Andrew Morton wrote:
> On Tue, 28 Feb 2012 23:40:45 +0400
> Konstantin Khlebnikov<khlebnikov@openvz.org> wrote:
>
>> This cpu hotplug hook was accidentally removed in commit v2.6.30-rc4-18-g00a62ce
>> ("mm: fix Committed_AS underflow on large NR_CPUS environment")
>
> That was a long time ago - maybe we should leave it removed ;) I mean,
> did this bug(?) have any visible effect? If so, what was that effect?
It's because cpu hotplug/unplug isn't widely used feature.
Visible effect -- some pages are borrowed in per-cpu page-vectors.
Truncate can deal with it, but these pages cannot be reused while this cpu is offline.
So this is like temporary memory leak.
>
> IOW, the changelog didn't give anyone any reason to apply the patch to
> anything!
Sorry, I'm just stuck in pile of patches. It seems I should stop and send them one by one.
This one isn't critical, so there no reasons for pushing it into stable branches.
next prev parent reply other threads:[~2012-03-01 8:06 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-28 19:40 [PATCH resend] mm: drain percpu lru add/rotate page-vectors on cpu hot-unplug Konstantin Khlebnikov
2012-02-28 19:40 ` Konstantin Khlebnikov
2012-02-29 0:37 ` KAMEZAWA Hiroyuki
2012-02-29 0:37 ` KAMEZAWA Hiroyuki
2012-02-29 20:38 ` Andrew Morton
2012-02-29 20:38 ` Andrew Morton
2012-03-01 8:06 ` Konstantin Khlebnikov [this message]
2012-03-01 8:06 ` Konstantin Khlebnikov
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