From: "Kirill A. Shutemov" <kirill@shutemov.name>
To: Sha Zhengju <handai.szj@gmail.com>
Cc: linux-mm@kvack.org, cgroups@vger.kernel.org,
KAMEZAWA Hiroyuki <kamezawa.hiroyu@jp.fujitsu.com>
Subject: Re: [PATCH] memcg: make threshold index in the right position
Date: Thu, 2 Feb 2012 14:27:47 +0200 [thread overview]
Message-ID: <20120202122747.GA12575@shutemov.name> (raw)
In-Reply-To: <4F2A6EBC.5090207@gmail.com>
On Thu, Feb 02, 2012 at 07:08:44PM +0800, Sha Zhengju wrote:
> On 02/02/2012 06:54 PM, Sha Zhengju wrote:
> >On 02/02/2012 06:14 PM, Kirill A. Shutemov wrote:
> >>On Thu, Feb 02, 2012 at 05:45:19PM +0800, Sha Zhengju wrote:
> >>>From: Sha Zhengju<handai.szj@taobao.com>
> >>>
> >>>Index current_threshold may point to threshold that just equal to
> >>>usage after __mem_cgroup_threshold is triggerd.
> >>I don't see it. Could you describe conditions?
> >>
> >It is because of the following code path in __mem_cgroup_threshold:
> >{
> > ...
> > i = t->current_threshold;
> >
> > for (; i >= 0 && unlikely(t->entries[i].threshold > usage); i--)
> > eventfd_signal(t->entries[i].eventfd, 1);
> > i++;
> >
> > for (; i < t->size && unlikely(t->entries[i].threshold <=
> >usage); i++)
> > eventfd_signal(t->entries[i].eventfd, 1);
> >
> > t->current_threshold = i - 1;
> > ...
> >}
> >
> >For example:
> >now:
> > threshold array: 3 5 7 9 (usage = 6)
> > ^
> > index
> >
> >next turn:
> > threshold array: 3 5 7 9 (usage = 7)
> > ^
> > index
> >
> >after registering a new event(threshold = 10):
> > threshold array: 3 5 7 9 10 (usage = 7)
> > ^
> > index
> Err.. Sorry for showing inaccurate index position... (may because of
> the mail format)
>
> now:
> threshold array: 3 [5] 7 9 (usage = 6, index = 5)
>
> next turn:
> threshold array: 3 5 [7] 9 (usage = 7, index = 7)
>
> after registering a new event(threshold = 10):
> threshold array: 3 [5] 7 9 10 (usage = 7, index = 5)
Good catch! Thank you.
Reviewed-by: Kirill A. Shutemov <kirill@shutemov.name>
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Kirill A. Shutemov
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next prev parent reply other threads:[~2012-02-02 12:26 UTC|newest]
Thread overview: 8+ messages / expand[flat|nested] mbox.gz Atom feed top
2012-02-02 9:45 [PATCH] memcg: make threshold index in the right position Sha Zhengju
2012-02-02 10:14 ` Kirill A. Shutemov
2012-02-02 10:54 ` Sha Zhengju
2012-02-02 11:08 ` Sha Zhengju
2012-02-02 12:27 ` Kirill A. Shutemov [this message]
2012-02-03 1:35 ` KAMEZAWA Hiroyuki
2012-02-03 2:49 ` Sha Zhengju
-- strict thread matches above, loose matches on Subject: below --
2012-02-02 7:58 Sha Zhengju
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